native plants

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Year of Pollination: Scarlet Gilia and Its Pollinators

Flowers that are visited and/or pollinated by hummingbirds typically fit the following description: petals are brightly colored, often red; petals are fused to form a long, narrow tube; a “landing pad” is absent; abundant nectar is produced deep within the flower; and fragrance is weak or nonexistent. Scarlet gilia (Ipomopsis aggregata) is a typical example of such a flower, and hummingbirds are indeed among its most common visitors. But there is so much more to the story.

Scarlet gilia (also commonly known as skyrocket) is a wildflower in the phlox family (Polemoniaceae) that occurs in many parts of western North America. It is considered a biennial or short-lived perennial. It spends the first year or so of its life as a compact rosette of fern-like leaves. Later it sends up a branched, flowering stem that can reach 5 feet tall or more. The flowers are slender, trumpet-shaped, and composed of five fused petals that flare outward creating five prominent, pointed lobes. They are self-incompatible and require a pollinator in order to set seed. The stamens of an individual flower produce mature pollen before the stigma of that flower is ready to receive it – this is called protandry and is one mechanism of self-incompatibility.

The rosette of scarlet gilia (Ipomopsis aggregata)

The rosette of scarlet gilia (Ipomopsis aggregata)

The flowering period of scarlet gilia can last several months. Depending on the location, it can begin in mid-summer and continue through the fall. During this period, it produces dozens of flowers. It is also at this time that it runs the risk of being browsed by elk, mule deer, and other animals. This doesn’t necessarily set it back though, as it has the potential to respond by producing additional flowering stalks and more flowers. Its flowers are visited by a variety of pollinators including bumblebees, hawkmoths, butterflies, syrphid flies, solitary bees, and of course, hummingbirds. But hummingbirds, in many parts of scarlet gilia’s range are migratory, and that’s where things get interesting.

Early flowers of scarlet gilia are usually red. As the season progresses, flowers slowly shift from red to pink. In some cases, they lose all pigmentation and become white. In the early 1980’s, pollination biologists Ken Paige and Thomas Whitman set out to determine the reason for this shift in flower color. They spent three years observing a population of scarlet gilia on Fern Mountain near Flagstaff, Arizona. They noted that the change in flower color corresponded with the migration of hummingbirds and that the now lighter colored flowers continued to be pollinated by hawkmoths until the end of the flowering season.

ipomopsis aggregata

A series of experiments and observations led them to conclude that hummingbirds prefer darker colored flowers and hawkmoths prefer lighter colored flowers. By shifting to a lighter flower color, scarlet gilia appeared to be taking advantage of remaining pollinators after hummingbirds had migrated. They also concluded that the color change was not the cause of hummingbird migration since other flowers with nectar-rich, red, tubular flowers (specifically Penstemon barbatus) remained available in the area throughout their migration. It was also noted that the flowers of scarlet gilia shifted the timing of nectar production, presumably to better match the behavior of hawkmoths which are more active in the evenings.

No plants were observed shifting from light colored flowers to dark colored flowers, which further supported their conclusion. They also compared the population they studied to populations that do not lose their hummingbird pollinator and noted that when hummingbirds remain, the flowers of scarlet gilia don’t change color.

Scarlet gilia (Ipomopsis aggregata) with white flowers

Scarlet gilia (Ipomopsis aggregata) with white flowers

But just how effective are hummingbirds as pollinators of scarlet gilia? A seperate study carried out by a different group of researchers determined that, while hummingbirds were “the most common floral visitor,” long-tongued bumblebees were the more effective pollinator when it came to pollen deposition and seed set. The study involved observations of a scarlet gilia population in Colorado over a 5 year period. Considering how well the floral traits of scarlet gilia match up with the hummingbird pollination syndrome, it is surprising to learn that long-tongued bumblebees are comparatively more effective at pollinating them.

This study provides further evidence against strict adherence to pollination syndromes and the most effective pollinator principle, both of which imply specialized plant-pollinator interactions. (I wrote about these topics here, here, and here in earlier Year of Pollination posts.) In their discussion, the authors propose two possible explanations as to why scarlet gilia, despite its phenotypic floral traits, does not appear to be specialized. One explanation is that “natural selection favors a specialized [floral] morphology that excludes all but a single type of visitor, but there are constraints on achieving this outcome.” Perhaps the pollinators aren’t cooperating; their opportunism is leading them to “exploit flowers on which they can realize an energetic profit, even if they do not mechanically ‘fit’ very well.” The “sensory abilities” of the pollinators may be “broadly tuned,” making it difficult for plants to develop flowers with “private signals detectable only by specific types of pollinators.”

The second explanation proposed by the authors is that “selection favors some degree of floral generalization, but that flowers can retain features that adapt them to a particular type of pollinator in spite of generalization.” In the case of scarlet gilia, specialization could be detrimental because after they send up their flower stalks, they are doomed to die. This gives them only one season to set seed, and if hummingbirds are either not available that year or only available in limited numbers, a scarlet gilia population can lose the opportunity to reproduce. As the authors put it, “the fact that individual plants enjoy only a single season of reproduction, suggests the value of ‘backup’ pollinators.” This may also explain why flower color shifts in order to take full advantage of hawkmoth pollination after hummingbirds are gone.

Scarlet gilia is not only a beautiful and widespread wildflower, but also a plant with a very interesting story. Follow the links below to learn more about this fascinating plant:

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Drought Tolerant Plants: Desert Willow

Hailing from dry washes and riverbanks of the desert southwestern United States and northern Mexico, desert willow is a tough tree or large shrub with delicate, showy flowers and wispy foliage. Its beauty and its ruggedness has made it a popular plant for dry gardens. It requires little attention maintenance-wise, yet attracts all kinds of attention otherwise. If you live in a desert climate that generally stays above 0 degrees Fahrenheit during the winter, this plant belongs in your garden.

Desert Willow - Chilopsis linearis

Desert Willow – Chilopsis linearis

A member of the family Bignoniaceae – a family that consists of at least 8o genera including catalpa (Catalpa spp.) and trumpet vine (Campsis spp.) – Chilopsis linearis is the sole member of its genus. The common name, desert willow, refers to its habitat and its long, slender, oppositely and alternately arranged leaves that resemble those of many willows (Salix spp.). Other common names include flowering willow, willowleaf catalpa, desert catalpa, and false-willow. There are two recognized subspecies – linearis and arcuata.

Desert willow is found most commonly in areas where seasonal flooding occurs. Known as desert dry washes – or simply dry washes or desert washes –  these are areas in the desert where runoff from heavy rains accumulates resulting in saturated soils followed by a prolonged dry period. Groundwater often remains accessible year-round to the deep roots of plants in this type of habitat. Desert willow shares this habitat with several other large shrubs and small trees including mesquite (Prosopis spp.), palo verde (Parkinsoinia spp.), and smoketree (Psorothamnus spinosus). Desert willow occurs along stream banks and river banks as well, where seasonal flooding also occurs.

Desert willow generally reaches a width of 10 to 15 feet and a height of at least 15 feet, although it has the potential to grow taller than 30 feet. It often has an open and sprawling or leaning habit, but it can be pruned to look more tree-like. Pruning can also result in more flowering, since flowers appear on new growth and pruning encourages growth. Watering this plant during the dry season can also lead to a flush of growth and more flowering. This is something to keep in mind, as it is the flowers that are the star of the show.

Persisting from late spring through midsummer (and sometimes longer), the 1 to 2 inch, trumpet-shaped, pink to rose to purple blossoms are hard to miss. They occur singularly or in clusters at the tips of branches. The ruffled-edges of the petals and the prominent streaks of color within the corolla tube add to the attraction. Hummingbirds, butterflies, and bumblebees are common visitors to these fragrant flowers. Summer rains or occasional watering can encourage flowering throughout the summer. Overwatering, on the other hand, can be detrimental.

The flowers eventually form long slender seed pods called capsules that reach up to 10 inches long. Inside the capsules are a series of hairy seeds. The hairs form small wings on the sides of the seeds. The seeds are eaten by a variety of bird species. Various species of birds can also be seen nesting in desert willow, and a variety of other animals use desert willow for browsing and/or for cover.

The fruits of Chilopsis linearis.

The fruits of Chilopsis linearis

The hairy, winged seeds of Chilopsis linearis

The hairy, winged seeds of Chilopsis linearis

Desert willow prefers sunny, southwest facing sites and tolerates most soil types. It performs best in soils that are well drained, low in organic content, and have a pH that is neutral to alkaline. The soil can be saturated at times, but should be given a chance to dry out – just like in its natural habitat. Avoid the impulse to add fertilizer.

Desert willow is said to be easy to propagate from cuttings or from seeds. It is commercially available, and several cultivars have been developed offering diverse flower colors and other special traits. It’s easy to grow, requires little attention, and provides an eye-catching floral show – all excellent reason to add this plant to your water-efficient landscape.

One tip from my experience seeing it survive the winters of southwestern Idaho: the deciduous leaves of Chilopsis linearis don’t reappear until very late in the spring – so late, in fact, that one might start to worry that the plant has perished. Don’t fret though; some winter kill is possible if sub-zero temperatures were experienced, but most likely it is still alive.

More information about desert willow:

–Encyclopedia of Life

–USDA Plant Guide

–Native Plant Information Network 

The photos in this post were taken at Idaho Botanical Garden in Boise, Idaho.

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Field Trip: Sawtooth Botanical Garden

columbine

It may only be a two and a half hour drive from my house, but until last week I had never visited Sawtooth Botanical Garden in Ketchum, Idaho. The garden is probably not in its prime in the middle of August, but I happened to be in the area so I had to check it out. It’s a small garden – about 5 acres – but I found the space to be well used and full of interesting plants and features. Walking through meandering pathways and around a series of berms, it is easy to get the impression that the garden is larger than it actually is. There were a few areas in obvious need of attention, but as an employee of a non-profit public garden myself, I understand the challenges of maintaining a garden with limited resources. So putting minor issues aside, I thought the garden looked beautiful and I greatly enjoyed my wander through it.

Sawtooth Botanical Garden is in its 11th year. Its mission is to “showcase native and cultivated plants that flourish at high altitude” and to “foster environmental stewardship” of the “region’s unique beauty” by offering “education, events, displays, and plant collections.” Read more about its mission and history here. Brief descriptions of the areas within the garden can also be found on the garden’s website. The interpretive signage describing each area in the garden was well done and one of the highlights of my visit. I didn’t stay long, but I definitely plan on visiting again in the near future. If you ever find yourself in the Wood River Valley, I highly recommend stopping by.

Central area of the garden featuring perennial beds and the Ellen Long Garden Pavillion

Central area of the garden featuring the perennial beds and the Ellen Long Garden Pavillion

Berms in the Alpine Garden with pathway passing through

Berms in the Alpine Garden with pathway passing through

Water feature in the Garden of Infinite Compassion, built in honor of the Dali Lama's visit to the Wood River Valley

Water feature in the Garden of Infinite Compassion, built in honor of the Dalai Lama’s visit to the Wood River Valley several years ago

Alpine strawberry (Fragaria sp.)

Alpine strawberry (Fragaria sp.)

Redtwig dogwood (Cornus stolonifera 'Baileyi')

The fruits of red twig dogwood (Cornus sericea ‘Baileyi’)

cinquefoil

Spring cinquefoil (Potentilla neumanniana)

Spiked speedwell (Veronica spicata 'Red Fox')

Spiked speedwell (Veronica spicata ‘Red Fox’)

Evening primrose (Oenothera sp.)

Evening primrose (Oenothera sp.)

 

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Weeds and Wildflowers of the Boise Foothills: June 2015

Boise, Idaho is a beautiful city for many reasons. One feature that makes it particularly attractive are the foothills that flank the city from the southeast to the northwest. The foothills are a transition zone to the mountains that lie to the northeast. Large sections of the foothills have been converted to housing, but much of the area remains as wide open space. There are around 150 miles of trails winding through the foothills that can be accessed from the Boise area. These trails are used frequently by hikers, mountain bikers, dog walkers, bird watchers, trail runners, and horseback riders. The foothills, along with so many other nearby attractions, explains why Boise is such an excellent city for those who love outdoor recreation.

boise foothills trail

I feel embarrassed to say that I had not yet made it into the foothills this year until about a couple weeks ago. I had intended to go for more frequent hikes this year, but life has been in the way. What I was especially curious to see was how the plant life in the foothills changes throughout the year. Because Boise is located in a high desert and receives very little precipitation (especially during the summer months), many of the local wildflowers show themselves in the spring when there is moisture in the soil, after which they wither up and go dormant for the rest of the year.

But there is still lots to see in June. However, it should be noted that when you are hiking in the foothills you must develop an appreciation for weeds, as many of the plants you will see are not native to this area and, in many cases, are in much greater abundance than the plants that are. Species brought in from Europe and Asia have become well established in the Boise Foothills, significantly altering the area’s ecology. One of the major changes has been wildfire frequency. Before weeds like cheatgrass – an annual, shallow-rooted grass imported from Europe – became so prolific in the area, fires were rare, slow moving, and isolated. The continuous, quick burning fuel source provided by dead cheatgrass heightens the risk of more frequent, faster moving, widespread fires, especially in the hot, dry summer months. This threatens plant species that are not adapted to frequent fires.

But this post isn’t about the ecology of the foothills. We can save that for another time. For now, I just wanted to share some of the plants I saw – both native and non-native – on my short walk through a very tiny corner of the Boise Foothills earlier this month.

The trail that I hiked is one of several trails in an area of the Boise Foothills called Hulls Gulch Reserve.

The trail that I hiked is one of several trails in an area of the Boise Foothills called Hulls Gulch Reserve.

 

Bachelor's Buttons (Centaurea cyanus) are native to Europe. They are a common cultivated flower and have escaped from yards into the foothills. They are quite attractive and popular among pollinators. Their flowers and stems are edible so perhaps we should all take to eating them.

Bachelor’s buttons (Centaurea cyanus) are native to Europe. They are a common cultivated flower and have escaped from yards into the foothills. They are quite attractive and popular among pollinators. Their flowers and stems are edible, so perhaps we should all take to eating them.

 

Silverleaf phacelia (Phacelia hastate) - a foothills native that is also a pollinator favorite.

Silverleaf phacelia (Phacelia hastata) – a foothills native and a pollinator favorite.

 

Pale evening primrose (Oenothera pallida) - a foothills native pollinated by nocturnal moths.

Pale evening primrose (Oenothera pallida) – a foothills native pollinated by nocturnal moths.

 

Medusahead (Taeniatherum caput-medusa) is an invasive annual grass from Eurasia. It has an ecological impact similar to cheatgrass (Bromus tectorum).

Medusahead (Taeniatherum caput-medusae) is an invasive annual grass from Eurasia. It has an ecological impact similar to cheatgrass (Bromus tectorum).

 

The fruits of nineleaf biscuitroot (Lomatium triternatum), a spring flowering plant in the carrot family (Apiaceae).

The fruits of nineleaf biscuitroot (Lomatium triternatum), a native spring wildflower in the carrot family (Apiaceae).

 

Fruits forming on antelope bitterbrush (Purshia tridentata), one of several shrubs native to the Boise Foothills.

Fruits forming on antelope bitterbrush (Purshia tridentata), one of several shrubs native to the Boise Foothills.

 

Rubber rabbitbrush (Ericameria nauseosa), a native shrub that flowers in late summer.

Rubber rabbitbrush (Ericameria nauseosa), a native shrub that flowers in late summer.

 

Lichens on the branch of basin big sagebrush (Artemisia tirdentata sbsp. tridentata) another common native shrub.

Lichens on the branches of basin big sagebrush (Artemisia tridentata subsp. tridentata), another common native shrub.

 

Tall tumblemustard (Sisymbrium altissimum) an introduced species and one of many tumbleweed species in the western states.

Tall tumblemustard (Sisymbrium altissimum) – an introduced species and one of many tumbleweed species in the western states.

 

Little spider atop the flowers of western yarrow (Achilea millefolium), a foothills native.

A little spider atop flowers of western yarrow (Achilea millefolium var. occidentalis), a foothills native.

Learn more about the Boise Foothills here and here.

Where have you been hiking lately?

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Year of Pollination: Stamen Movement in the Flowers of Prickly Pears

Last week I made an effort to convince you to add a prickly pear or two to your water-wise gardens. One standout reason to do this is their strikingly beautiful flowers. Apart from being lovely to look at, many prickly pear flowers have a distinct feature that makes them quite fascinating. A demonstration of this feature can be seen in the following video.

 

Stamen movement in response to touch is a characteristic of many species in the genus Opuntia. It isn’t exclusive to Opuntia, however, and can also be seen in Berberis vulgaris, Portulaca grandiflora, Talinum patens, among others. Knowing this makes me want to touch the stamens of any flower I can find just to see what will happen.

The response of stamens to touch has been known for at least a few centuries, but recent research is helping us gain a better understanding of how and why this phenomenon occurs. In general, this movement is thought to assist in the process of cross-pollination. In some cases it may also aid in self-pollination. Additionally, it can have the effect of protecting pollen and nectar from “robbers” (insects that visit flowers to consume these resources but that do not provide a pollination service). Quite a bit of research has been done on this topic, so to simplify things I will be focusing on a paper published in a 2013 issue of the journal, Flora.

In their paper entitled, Intriguing thigmonastic (sensitive) stamens in the plains prickly pear, Cota-Sanchez, et al. studied the flowers of numerous Opuntia polyacantha individuals found in three populations south of Saskatoon, Saskatchewan, Canada. Their objective was to “build basic knowledge about this rather unique staminal movement in plants and its putative role in pollination.” They did this by conducting two separate studies. The first involved observing flower phenology and flower visitors and determining whether the staminal movement is a nasty (movement in a set direction independent of the external stimulus) or a tropism (movement in the direction of the external stimulus). The second involved using high-powered microscopes to analyze the morphology of the stamens to determine any anatomical traits involved in this movement. While the results of the second study are interesting, for the purposes of this post I have chosen to focus only on the findings of the first study.

An important note about the flowers of O. polyacantha is that they are generally protandrous, meaning that the anthers of a single flower release pollen before the stigmas of that same flower are receptive. This encourages cross-pollination. An individual flower is only in bloom for about 12 hours (sometimes as long as 30 hours), however flowering doesn’t occur all at once. The plants in this study flowered for several weeks (from the second week of June to the middle of July).

To determine whether the staminal movement is a nasty or a tropism, the researchers observed insects visiting the flowers. They also manually stimulated the stamens with various objects including small twigs, pencils, and fingers, touching either the inner sides of the filaments (facing the style) or the outer sides (facing the petals). In every observation, the stamens moved in the same direction, “inwards and towards the central part of the flower.” This “consistent unidirectional movement, independent of the area stimulated” led the researchers to categorize the staminal movement of O. polyacantha as thigmonastic. They also observed that staminal movement slowed as the blooming period of an individual flower was coming to an end – “and finally when all the anthers had dehisced, the anthers rested in a clustered position, marking the end of anthesis.” Furthermore, it was observed that “filaments move relatively faster in sunny, warm conditions as opposed to cloudy, cold and rainy days.”

The researchers went on to discuss unique features of the stamens of O. polyacantha. Specifically, the lower anthers contain significantly more pollen than the upper anthers. When the stamens are stimulated, their movement towards the center of the flower results in the lower anthers becoming hidden below the upper anthers. They also noted that small insects less than 5 millimeters in size did not trigger stamen movement. Further observations of the insect vistors helped explain these phenomena.

SAMSUNG

A “broad diversity of insects” was observed visiting the flowers, from a variety of bees (bumblebees, honeybees, sweat bees, and mining bees) to bee flies, beetles, and ants. The large bees  were determined to be the effective pollinators of this species of prickly pear. Their large weight and size allows them to push down through the upper anthers to the more pollen-abundant anthers below. After feeding on pollen and nectar, they climb out from the stamens and up to the stigma where they take off, leaving the flower and depositing pollen as they go. Because the bees are visiting numerous flowers in a single flight and the flowers they visit are protandrous, pollen can be transferred from one flower to another and self-pollination can be avoided.

Beetles were observed to be the most common visitors to the flowers; however, they were not seen making contact with the stigma and instead simply fed on pollen and left. Ants also commonly visit the flowers but largely remain outside of the petals, feeding from “extranuptial nectaries.” In short, beetles and ants are not recognized as reliable pollinators of this plant.

Similar results involving two other Opuntia species were found by Clemens Schlindwein and Dieter Wittmann. You can read about their study here.

There are lots of flower anatomy terms in this post. Refresh your memory by visiting another Awkward Botany post: 14 Botanical Terms for Flower Anatomy.

Recently I received a note from a reader requesting that I include a link to subscribe to this blog’s RSS Feed. I have now made that available, and it can be found at the top of the sidebar.

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Drought Tolerant Plants: Prickly Pears

In the introduction to this series about drought tolerant plants, I defended water efficient gardens by claiming they don’t have to be the “cacti-centric” gardens that many visualize upon hearing terms like “xeriscape,” “water-wise,” and “drought tolerant.” And this is absolutely true. However, that won’t stop me from suggesting that such landscapes include a cactus or two. Despite their menacing and potentially dangerous spines, they are actually quite beautiful, and a cactus in bloom is really a sight to behold. Together with a variety of grasses, herbaceous flowering plants, and shrubs, cactus can add unique forms, textures, and focal points that will enhance the look and function of a water-wise garden. This is why I recommend considering cactus, particularly (as far as this post is concerned) one of the many varieties of prickly pears.

The cactus family (Cactaceae) has a native range that is limited to the Americas. Within that range it is expansive, and cactus species can be found in diverse regions from Canada down to Patagonia. The genus Opuntia (the prickly pears) is the most widespread of any genus in the cactus family consisting of at least 300 species found throughout the Americas. Even a brief investigation into Opuntia will reveal that there is considerable controversy as to how many species there actually are and what to call them. This is partly due to the large ranges that species in this genus can have and the diverse habitats they can be found in within those ranges, resulting in a single species having many forms, varieties, and/or subspecies. Hybridization is also common in this genus where ranges overlap, augmenting the challenge of identification.

Generally, prickly pears have flattened stems with spines and glochids emerging from small bumps called areoles. Their flowers are large, showy and a shade of either yellow, orange, or pink and sometimes white. They form fruits that are either fleshy and juicy with a red or purple hue or hard, dry and a shade of brown or tan. The flattened stems are called pads or cladodes and can be quite large in some species, while diminutive and sometimes rounded in others. Some species are without spines, but all have glochids – tiny, barbed, hair-like structures found in clusters on the stems and fruits. While the spines can be painful when they penetrate skin, the glochids are far more irritating as they easily detach themselves from the plant and work their way into the skin of their victims. The fleshy fruits, called tunas, can be eaten after first taking care to remove the glochid-infested outer layer. The young stems of many species can also be eaten – they are referred to as nopales and are common in Mexican cuisine.

Flowers of Opuntia sp. with bee inside flower on the left

Flowers of Opuntia sp. with bee inside flower on the left

Again speaking generally, prickly pears are very easy to propagate and cultivate. Their two main preferences are full sun and well-drained soil. If you are worried that the soil you are planting them in is going to stay too wet for too long, amend it with some gravel. This is especially important if you live in a climate that receives lots of precipitation or that has cold, wet winters. Once established, prickly pears will move around the garden. If that becomes a problem, expanding plants are easily pruned and traveling plants are easily removed.

I live in a climate that requires the selection of cold hardy prickly pears, so I am taking my specific recommendations from two books: Cacti and Succulents for Cold Climates by Leo J. Chance and Hardy Succulents by Gwen Moore Kelaidis. If you live in a warmer climate, your options will be greater. Still, the options for cold regions are pretty numerous, so for the sake of space I am narrowing my list down to a handful that stand out to me at this particular moment.

Three eastern United States species of prickly pears (O. compressa, O. macrorhiza, and O. humifusa) are, according to Chance, “more capable of dealing with wet and cold conditions than almost any other members of the cactus family.” They still require well-drained soil though. An appealing trait is their large, juicy, red fruits that can add garden interest in late summer and fall. Opuntia engelmannii is another species with the potential to tolerate cold, wet conditions. Its size is appealing to me, with pads that reach a foot wide and plants that grow several feet tall. Chance advises finding “a clone that is known to be cold tolerant” and making some space for it, “as it becomes huge in time.” The most cold tolerant prickly pear may be Opuntia fragilis. It is a diminutive plant with a large native range and a variety of forms, some with rounded pads “shaped like marbles.”

Fruits ("tunas") of Opuntia engelmannii - photo credit: www.eol.org

Fruits (“tunas”) of Opuntia engelmannii – photo credit: www.eol.org

Opuntia fragilis 'Frankfurt' - photo credit: wikimedia commons

Opuntia fragilis ‘Frankfurt’ – photo credit: wikimedia commons

Opuntia polyacantha is a prickly pear native to my home state, Idaho. It is found at high elevations throughout the Intermountain West and is also found on the Great Plains. It has many forms and varieties, and its flowers are various shades of pink or yellow. It is a fast growing species and spreads around easily. Other cold hardy species include Opuntia macrocentra (which has a very attractive yellow flower with a red-orange center), Opuntia erinacea (commonly known as hedgehog prickly pear for its abundant, long spines that can obscure the pads), and Opuntia microdisca (a tiny Argentinian prickly pear with pads that barely reach an inch across but, as Chance says, “works very well in a dry rock garden with other miniatures”).

Pads of Opuntia polyacantha

Pads and spines of Opuntia polyacantha

A post about Opuntia could go on indefinitely due to the sheer number of species and their diverse forms and attributes. This is meant merely to pique your interest. The flowers, if nothing else, should certainly interest you. In her book, Kelaidis calls them “improbably beautiful,” and goes on to say that they are “often papery, always glistening and showy.” Chance likens them to “any fancy rose” because they are “extraordinarily large, brightly colored, [and] eye catching.” Next week, as part of Awkward Botany’s Year of Pollination, I will present another reason to be fascinated with the flowers of Opuntia. For now, I will leave you to ponder this word, “thigmonasty.”

Want to learn more about prickly pears? Check out Opuntia Web.

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A Rare Hawaiian Plant – Newly Discovered and Critically Endangered

Hawaii is home to scores of plant species that are found nowhere else in the world. But how did those plants get there? In geological time, Hawaii is a relatively young cluster of islands. Formed by volcanic activity occurring deep within the ocean, they only just began to emerge above water around 10 million years ago. At that point the islands would have been nearly devoid of life, and considering that they had never been connected to any other body of land and are about 2,500 miles away from the nearest continent, becoming populated with flora and fauna took patience and luck.

As far as plant life is concerned, seeds and spores had to either be brought in by the wind, carried across the ocean by its currents, or flown in attached to the feathers of birds. When humans colonized the islands, they brought seeds with them too; however, its estimated that humans didn’t begin arriving on the islands until about 1,700 years ago. The islands they encountered were no longer barren landscapes, but instead were filled with a great diversity of plant and animal life. A chance seed arriving on the islands once in a blue moon does not fully explain such diversity.

This is where an evolutionary process called adaptive radiation comes in. A single species has the potential to diverge rapidly into many new species. This typically happens in new habitats where little or no competition exists and there are few environmental stresses. Over time, as genetic diversity builds up in the population, individuals begin to adapt to specific physical factors in the environment, such as soil type, soil moisture, sun exposure, and climate. As individuals separate out into these ecological niches, they can become reproductively isolated from other individuals in their species and eventually become entirely new species.

This is the primary process that led to the great floral diversity we now see on the Hawaiian Islands. Adaptive radiations resulted in more than 1000 plant species diverging from around 300 seed introductions. Before western colonization, there were more than 1,700 documented native plant species. Much of this diversity is explained by the rich diversity of habitats present on the volcanic islands, which lead to many species becoming adapted to very specific sites and having very limited distributions.

A small population size and a narrow endemic range is precisely the reason why Cyanea konahuanuiensis escaped detection until recently. In September 2012, researchers on the island Oahu arrived at a drainage below the summit of Konahua-nui (the tallest of the Ko’olau Mountains). They were surveying for Cyanea humboldtiana, a federally listed endangered species that is endemic to the Ko’olau Mountains. In the drainage they encountered several plants with traits that differed from C. humboldtiana, including hairy leaves, smooth stems, and long, hairy calyx lobes. They took pictures and collected a fallen leaf  for further investigation.

Ko'olau Mountains of O'ahu (photo credit: wikimedia commons)

Ko’olau Mountains of O’ahu (photo credit: wikimedia commons)

Initial research suggested that this was a species unknown to science. More information was required, so additional trips were made, a few more individuals were found, and in June 2013, a game camera was installed in the area. The camera sent back three photos a day via cellular phone service and allowed the team of researchers to plan their next trip when they were sure that the flowers would be fully mature. Collections were kept to a minimum due to the small population size; however, using the material they could collect, further analyses and comparisons with other species in the Cyanea genus and related genera demonstrated that it was in fact a unique species, and so they gave it the specific epithet konahuanuiensis after the mountain on which it was found. It was also given a common Hawaiian name, Haha mili’ohu, which means “the Cyanea that is caressed by the mist.”

The hairy flowers and leaves of Cyanea konahuanuiensis. Purple flowers appear June-August. (photo credit: www.eol.org)

The hairy flowers and leaves of Cyanea konahuanuiensis. Purple flowers appear June-August. (photo credit: www.eol.org)

The total population of Cyanea konahuanuiensis consists of around 20 mature plants and a couple dozen younger plants. It is considered “critically imperiled” and must overcome some steep conservation challenges in order to persist. To start with, the native birds that pollinate its flowers and disperse its seeds may no longer be present. Also, it is likely being eaten by rats, slugs, and feral pigs. Add to that, several invasive plant species are found in the area and are becoming increasingly more common. While the researchers did find some seedlings in the area, all of the fruits that they observed aborted before they had reached maturity. Lastly, the population size is so small that the researchers say a landslide, hurricane, or flash flood “could obliterate the majority or all of the currently known plants with a single event.”

Seeds collected from immature fruits from two plants were sown on an agar medium at the University of Hawaii Harold L. Lyon Arboretum. The seeds germinated, and so the researchers plan to continue to collect seeds “in order to secure genetic representations from all reproductively mature individuals in ex situ collections.”

Single stem of Cyanea konahuanuiensis (photo credit: www.eol.org)

Single stem of Cyanea konahuanuiensis (photo credit: www.eol.org)

C. konahuanuiensis is not only part of the largest botanical radiation event in Hawaii, but also the largest on any group of islands. At some point in the distant past, a single plant species arrived on a Hawaiian island and has since diverged into at least 128 taxa represented in six genera, Brighamia, Clermontia, Cyanea, Delissea, Lobelia, and Trematolobelia, all of which are in the family Campanulaceae – the bellflower family. Collectively these plants are referred to as the Hawaiian Lobelioids. Cyanea is by far the most abundant genus in this group consisting of at least 79 species. Many of the lobelioids have narrow distributions and most are restricted to a single island.

Sources

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Poisonous Plants: Baneberry

For all the benefits that plants offer humanity – the distillation being that Earth would be uninhabitable without them – there is still reason to be wary of them. In a world lousy with herbivores, plant species that are unpalatable have a greater chance of survival. Inflicting serious injury or death upon being ingested – or even by coming in contact with an unsuspecting visitor – offers even greater assurance that a plant will survive long enough to reproduce, passing along to its progeny any traits that led to its superior fitness. The traits in this case are chemical compounds that can be toxic when delivered at the right dose to the right organism. This is the nature of poisonous plants, and the reason why from a young age we were all likely warned not to eat every tasty looking berry we come across and not to go tromping carelessly through an area where certain plants might be present. Plants aren’t out to get us per se, but some do have the potential to cause us great harm. Informing ourselves and taking precautions is advised.

This is the first in a series of posts about poisonous plants. The list of poisonous plants is long, so it’s going to take a while to get through them all. There are some plants that are not generally considered poisonous but can cause illness or death to those who are allergic to them – like peanuts. I don’t plan to include such plants, but there may be some exceptions along the way. The popular author Amy Stewart wrote a book about poisonous and other nefarious plants entitled, Wicked Plants: The Weed that Killed Lincoln’s Mother and other Botanical Atrocities. Below is an excerpt from her introduction to that book that I thought would be worth including here:

Do not experiment with unfamiliar plants or take a plant’s power lightly. Wear gloves in the garden; think twice before swallowing a berry on the trail or throwing a root into a stew pot. If you have small children, teach them not to put plants in their mouths. If you have pets, remove the temptation of poisonous plants from their environment. The nursery industry is woefully lax about identifying poisonous plants; let your garden center know that you’d like to see sensible, accurate labeling of plants that could harm you. Use reliable sources to identify poisonous, medicinal, and edible plants. (A great deal of misinformation circulates on the Internet, with tragic consequences.)

Baneberry (Actaea spp.)

“Bane” is defined as deadly poison or a person or thing that causes death, destruction, misery, distress, or ruin. The word seems fitting as a common name to describe a plant with a berry that when ingested is said to have an almost immediate sedative effect on the heart and can ultimately lead to cardiac arrest. Baneberry is a name given to several plants in the genus Actaea, two of which are the main focus of this post – red baneberry (Actaea rubra) and white baneberry (Actaea pachypoda).

Actaea is in the family Ranunculaceae – the buttercup family – a family that consists of several common ornamental plants including those in the genera Ranunculus, Delphinium, and Clematis. A. rubra and A. pachypoda are commonly found in the understory of wooded areas in North America – A. rubra is the most widespread of the two species, occurring throughout North America except Mexico and the southeastern U.S. states; A. pachypoda occurs in eastern Canada and most eastern and Midwestern U.S. states.

The flowers of red baneberry, Actaea rubra (photo credit: wikimedia commons)

The flowers of red baneberry, Actaea rubra (photo credit: wikimedia commons)

Red baneberry is an herbaceous perennial that emerges in the spring from a basal stem structure called a caudex or from a rhizome, dying back to the ground again in the fall. One or several branching stems reach from 1 to 3 feet high, each with compound leaves consisting of 2-3 leaflets. The leaflets are deeply lobed and coarsely toothed. Several small, white flowers appear in spring to early summer clustered together in an inflorescence called a raceme. The petals are inconspicuous, but the stamens are large and showy. The flowers are said to have a rose-like scent. A variety of insects pollinate the flowers, after which green berries form, turning red or occasionally white by mid to late summer.

The berries of red baneberry, Actaea rubra (photo credit: www.eol.org)

The berries of red baneberry, Actaea rubra (photo credit: www.eol.org)

Red baneberry occurs on diverse soil types and in diverse ecosystems across its expansive native range. It seems to prefer, moist, shady, nutrient rich, acidic sites, and is considered an indicator of such places. It can be found in deciduous, coniferous, and mixed forested areas. Its preference for moist sites means that it can also be found in swamps, along stream banks, and in other riparian areas.

White baneberry has a relatively smaller native range and is found in very similar environments. It also has many of the same features and habits as red baneberry, with the main distinction being its striking white berries formed on prominent, stout, bright red axes and peduncles (the “stems” and “branches” of the racemes). The stigmas are persistent on the berries, forming large black dots on each berry and giving it another common name, doll’s eyes. This is a feature of red baneberry as well, but is much more striking on the white berries.

Baneberry is occasionally browsed by livestock and wildlife including deer, elk, and small mammals. However, it has a low degree of palatability and isn’t very nutritious. Birds, unaffected by their poisonous qualities, eat the berries and are the main seed dispersers of baneberry.

The berries of white baneberry or doll's eyes Actaea pachypoda (photo credit: www.eol.org)

The berries of white baneberry or doll’s eyes, Actaea pachypoda (photo credit: www.eol.org)

The roots and berries are the most poisonous parts of baneberry, however all parts are toxic. The berries are quite bitter, so it is not likely that one would eat enough of them to receive a severe reaction. If ingested, symptoms include stomach cramps, dizziness, vomiting, diarrhea, delirium, and circulatory failure. Eating six or more berries can result in respiratory distress and cardiac arrest. The toxin in the plant has yet to be clearly identified. Protoanemonin is present, as it is in all plants in the buttercup family, but the real toxicity of the plant is probably due to an essential oil or a poisonous glycoside. There have been no reported deaths due to the consumption of red or white baneberry, but a European species of baneberry (A. spicata) has been linked to the death of several children.

Native Americans were aware of baneberry’s toxicity, so rather than use it as a food source, they used it medicinally. Among other things, the root was used as a treatment for menstrual cramps, postpartum pain, and issues related to menopause, and the berry was used to induce vomiting and diarrhea and as a treatment for snakebites. Leaves were chewed and applied to boils and wounds. Two websites I visited claimed that arrowheads were dipped in the juice of the berries to make poison arrows. Neither cited a reference, and in the section on arrow poisons in Wicked Plants, Stewart doesn’t mention baneberry. However, that doesn’t mean it didn’t happen.

What do you fear the most? Batman villian, Bane, or baneberry? (photo credit: Comic Vine)

What do you fear the most? Batman villian, Bane, or baneberry? (photo credit: Comic Vine)

References

 

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Texas State Flower

The state flower of Texas blooms in early spring. At least most of them do anyway. Some don’t bloom until late spring and others bloom in the summer. The reason for the staggered bloom times is that the state flower of Texas is not one species but six. All are affectionately referred to as bluebonnets and all are revered by Texans.

As the story goes, at the beginning of the 20th century the Texas legislature set out to determine which flower should represent their state. One suggestion was the cotton boll, since cotton was a major agricultural crop at the time. Another suggestion was a cactus flower, because cacti are common in Texas, are long-lived, and have very attractive flowers. A group of Texas women who were part of the National Society of Colonial Dames of America made their pitch for Lupinus subcarnosus, commonly known as buffalo clover or bluebonnet. Ultimately, the nomination from the women’s group won out, and bluebonnets became an official state symbol.

The debate didn’t end there though. Many people thought that the legislature had selected the wrong bluebonnet, and that the state flower should be Lupinus texensis instead. Commonly known as Texas bluebonnet, L. texensis is bigger, bolder, and more abundant than the comparatively diminutive L. subcarnosus. This debate continued for 70 years until finally the legislature decided to solve the issue by including L. texensis “and any other variety of bluebonnet not heretofore recorded” as the state flower of Texas.

Lupinus texensis - Texas bluebonnet

Lupinus texensis (Texas bluebonnet) bravely growing in Idaho

According to Mr. Smarty Plants, the list of Texas state flowers includes (in addition to the two already mentioned)  L. perennis, L. havardii, L. plattensis, and L. concinnus. Most on this list are annuals, and all are in the family Fabaceae – the pea family. Plants in this family are known for their ability to convert atmospheric nitrogen into plant available nitrogen with the help of a soil dwelling bacteria called rhizobia. The genus Lupinus includes over 200 species, most of which are found in North and South America. Others occur in North Africa and the Mediterranean. Plants in this genus are popular in flower gardens, and there are dozens of commercially available hybrids and cultivars.

L. subcarnosus is sometimes referred to as sandy land bluebonnet and occurs mainly in sandy fields and along roadsides. L. texensis is a Texas endemic; its native range includes the prairies and open fields of north and south central Texas. It is now found throughout Texas and bordering states due to heavy roadside plantings. L. perennis is the most widespread Texas bluebonnet, occurring throughout the eastern portion of the U.S. growing in sand hills, woodland clearings, and along roadsides. L. havardii is the largest of the Texas bluebonnets. It has a narrow range, and is found in a variety of soil types.  L. plattensis is a perennial species and occurs in the sandy dunes of the Texas panhandle. L. concinnus is the smallest of the Texas bluebonnets and is found mainly in sandy, desert areas as well as some grasslands.

Lupinus concinnus (...) - photo credit: www.eol.org

Lupinus concinnus (Nipomo Mesa lupine) – photo credit: www.eol.org

A legend surrounds the rare pink bluebonnet.

A legend surrounds the rare pink bluebonnet

Read more about Texas bluebonnets here and here.

“I want us to know our world. If I lived in north Georgia on up through the Appalachians, I would be just as crazy about the mountain laurel as I am about bluebonnets.” – Lady Bird Johnson

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Field Trip: Lady Bird Johnson Wildflower Center, part two

This is the second in a series of two posts about my recent trip to Lady Bird Johnson Wildflower Center in Austin, Texas. You can read the first post here. Both posts are comprised of mostly pictures, as they tell a much better story about the place then my words can. However, even pictures don’t do the place justice; it’s definitely a site that you are going to have to see for yourself. I highly recommend it.

One name that kept coming up during the native plant conference was Doug Tallamy – and for good reason. Tallamy has long promoted and encouraged the use of native plants in landscapes, largely for the creation of wildlife habitat in urban and suburban areas. In 2007 he put out a book entitled, Bringing Nature Home: How You Can Sustain Wildlife with Native Plants, in which he made a strong argument for native plant gardens. His book and lectures have inspired many to seek out native plants to include in their yards. What was lacking in his book, however, was detailed information on the horticulture and design aspects of using native plants. So in 2014, together with Rick Darke, Tallamy put out The Living Landscape, an impressive tome outlining how to create beautiful and functional gardens using native plants. Both books are well worth your time.

The plant name following each photo or series of photos links to a corresponding entry in the Native Plant Database which is managed by the Wildflower Center’s Native Plant Information Network. The quotes that accompany the plant names are taken from the Native Plant Database entries.

Ilex vomitoria (yaupon). “The leaves and twigs contain caffeine, and American Indians used them to prepare a tea which they drank in large quantities ceremonially and then vomited back up, lending the plant its species name, vomitoria. The vomiting was self-induced or because of other ingredients added; it doesn’t actually cause vomiting.”

aesculus pava var pava 3

Aesculus pavia var. pavia (red buckeye). “Long popular for its brilliant, hummingbird-attracting spring flowers and rich green foliage, it is found in nature most often as a plant of woodland edges, where it can get morning sun and afternoon shade.”

tillandsia recurvata 5

Tillandsia recurvata (ball moss). An epiphyte commonly found on trees within its range, including Quercus fusiformis (escarpment live oak) a dominant tree at the Wildflower Center. “Some have been introduced into other warm regions and cultivated for use as ornamentals or for their edible fruit.”

Opuntia ellisiana (spineless prickly pear). A spineless form of Opuntia cacanapa derived from cultivation. “The spineless prickly pear is a great addition to the landscape for those seeking a cactus form, showy blooms, and bright red cactus fruits (tunas). Beware, although it doesn’t have long sharp spines, the tiny glochids (slivers) are very irritating to the skin if the plant is not handled correctly.”

Gelsemium sempervirens (Carolina jessamine). “The flowers, leaves, and roots are poisonous and may be lethal to humans and livestock. The species nectar may also be toxic to honeybees if too much is consumed, and honey made from Carolina jessamine nectar may be toxic to humans.”

Lonicera sempervirens (coral honeysuckle). “Flowers attract hummingbirds, bees, and butterflies. Fruits attract quail, purple finch, goldfinch, hermit thrush, and American robin.”

windmill