pollinators

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Exploring Pollination Biology in Southwestern China

This is the sixth in a series of posts reviewing the 17 articles found in the October 2014 Special Issue of American Journal of Botany, Speaking of Food: Connecting Basic and Applied Science.

Insect Pollination and Self-Incompatibility in Edible and/or Medicinal Crops in Southwestern China, a Global Hotspot of Diversity by Zong-Xin Ren, Hong Wang, Peter Bernhardt, and De-Zhu Li

We rely on pollinators to pollinate at least 75% of our food crops, which is why any talk of pollinator decline tends to make us nervous. It is also why research involving pollinators and pollination is so important. Despite all we know, there is still so much to learn. The authors of this study, recognizing that “there are large gaps in the study of the pollination of economically important and traditionally grown species in China,” set out to help close these gaps. Their research not only has the potential to benefit agricultural communities in China, but also adds to our growing understanding of pollination biology – a science that has become increasingly important in an age of human population growth and shifting climates.

The incredibly diverse Chinese flora includes at least 31,000 plant species. Three hundred of the 1500 species of worldwide cultivated crop plants “originated and/or were domesticated and/or underwent differentiation in China.” Southwestern China has a particularly large amount of botanical diversity and is considered a biodiversity hotspot. In this study concerning agricultural pollination, researchers chose to focus on Yunnan, a province in southwestern China. They chose this region due to its high level of current and historical agriculture and because it is “one of the last refuges of the eastern Asian honeybee, Apis cerana, in China.” They narrowed their research down to 11 species that are important for their culinary and/or medicinal use, some of them having widespread use and others having more local, cultural use. Depending on the species, conclusions were drawn either from available literature, from field studies, or both.

Eastern Asian Honeybee (Apis cerana) on Citrus limonia flowers (photo credit: www.eol.org)

Eastern Asian Honeybee (Apis cerana) on Citrus limonia flowers (photo credit: www.eol.org)

A review of the literature revealed information about each plant’s breeding system, the pollinators involved, ethnobotanical details, and other things. No information was available on the breeding system or pollinators of Panax notoginseng, “one of the most highly valued Chinese medicinal herbs.” Five species were found to be self-compatible (Angelica sinensis, Amomum tsao-ko, Brassica napus, B. campestris, and Gastrodia elata) and four were found to be self-incompatible (Camellia oleifera, Dendrobium catenatum, Fagopyrum esculentum, and Paris plyphylla var. yunnanensis). Codonopsis subglobosa was somewhere in the middle. The authors were intrigued by the persistent self-incompatibility in these domesticated plants (some more recently domesticated than others), noting that “both traditional and modern agricultural practices in China could not always overcome ancestral self-incompatibility mechanisms.” A running theme seemed to be that, if able to produce fruit or seed when hand-pollinated or without the aid of pollinators, the plants consistently performed better when insect pollinated. One of the most interesting findings was that Gastrodia elata, Dendrobium catenatum, and Paris plyphylla var. yunnanensis “persist in cultivation only through hand-pollination.”

Camellia oleifera, tea-oil plant, is pollinated by two native solitary bee species. It is avoided by native and introduced honeybees because its nectar contains substances that are toxic to worker bees, including caffeine, raffinose, stachyose, and galactose. Fagopyrum esculentum, common buchwheat, is native to southern China and was likely first domesticated there. It is pollinated by a variety of insects; however, its main pollinator in worldwide cultivation is the European honeybee, Apis mellifera. In China, evidence suggests that when pollinated by native pollinators, buckwheat produces higher yields and larger fruits. Codonopsis subglobosa is an undomesticated but cultivated perennial vine endemic to southwestern China, the roots of which are used as a substitute for ginseng. It can self-pollinate without a vector, but cross-pollination by wasps yields more seeds. Pollination by “hunting wasps” is rare, and C. subglobosa is not the only plant in the area pollinated by them. If the “evolution of hunting wasp pollination systems has evolved repeatedly in unrelated species native to southwestern China,” this region may be a “center for the convergent evolution of hunting wasp pollination.”

Common Buckwheat, Fagopyrum esculentum (photo credit: Wikimedia commons)

Common Buckwheat, Fagopyrum esculentum (photo credit: wikimedia commons)

Beekeeping has been a major part of agriculture in China for centuries. However, the introduction of the European honeybee has caused a significant decline in both wild and managed populations of native honeybees, despite native honeybees being “better adapted to more diffuse nectar resources” than the introduced honeybee. The decline in keeping and managing native honeybees is complicated and involves much more than just the introduction of the European honeybee. Along with the debate about what is best for agriculture in China, is the concern about what introducing non-native pollinators could mean for native flora and fauna. The authors conclude that there is “urgent need for new pollination management policies in China.”

This article ends with suggestions about how to improve and expand pollination biology research in China in order to fill gaps in knowledge, improve agricultural production, and protect and conserve native biodiversity. China is an ideal candidate for such research for several reasons: it has areas like southwestern China that are very species rich, it has a long history of agriculture, and it has numerous unique crops that are specific to Chinese culture. China also has a large and growing population, so improvements that can lead to more sustainable agricultural production will be greatly beneficial in the long run.

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Our Backyard Farm and Garden Show: Fall 2014

I had every intention of documenting this year’s garden more thoroughly, but as things tend to go, the days got busy and the year got away from me. Now here we are in mid-October, still waiting for the first frost but accepting its imminence, watching reluctantly as another growing season comes to a close. We took several pictures but few notes, so what follows is a series of photos and a few reflections on what transpired this past year in, what Flora likes to call, Our Backyard Farm and Garden Show.

Abundance

Abundance

I guess I should start at the beginning. Last year I was living in an apartment. I was growing things in two small flower beds and a few containers on my patio. That had been my story for about a decade – growing what I could on porches and patios and in flower beds of various apartments in a few different parts of the country. At one point I was living in an apartment with no space at all to grow anything, and so I attempted to start a garden in the backyard of an abandoned, neighboring house – geurilla gardening style – but that didn’t go so well. At another location I had a plot at a community garden. The three years I spent there were fun, but definitely not as nice as stepping outside my door and into my garden.

Earlier this year, I moved in with Flora. She was renting a house with a yard, so when I joined her, I also joined her yard. Flora is a gardener, too; she had spent her first year here growing things in the existing garden spaces but wanted to expand. So we did. We enlarged three beds considerably and built four raised beds and two compost bins. We also got permission to grow things in the neighbor’s raised beds. And that’s how our growing season started – coalescence and expansion.

Then summer happened. It came and went, actually. Most days were spent just trying to keep everything alive – moving sprinklers around, warding off slugs and other bugs, and staking things up. Abundance was apparent pretty much immediately. We started harvesting greens (lettuce, kale, collards, mustards) en masse. Shortly after that, cucumbers appeared in concert with beets, turnips, basil, ground cherries, eggplants, tomatoes, carrots, peppers, etc. Even now – anticipating that first frost – the harvest continues. We are uncertain whether or not we will remain here for another growing season; regardless, we are considering the ways in which we might expand in case we do. Despite the amount of work that has gone into our garden so far, we still want to do more. Apparently, our love of gardening knows no bounds.

A view of our side yard. It is pretty shady in this section of the yard but we were still able to grow kale and collards along with several different flowers and herbs.

A view of our side yard. It is pretty shady in this bed but we were still able to grow kale and collards along with several different flowers and herbs.

 

We grew several varieties of lettuce. This is one that I was most excited about. It's called 'Tennis Ball.' It is a miniature butterhead type that Thomas Jefferson loved and used to grow in his garden at Monticello.

We grew many varieties of lettuce. This is one that I was most excited about. It’s called ‘Tennis Ball.’ It is a miniature butterhead type that Thomas Jefferson loved and grew in his garden at Monticello.

 

'Shanghai Green' Pak Choy

‘Shanghai Green’ Pak Choy

 

'Purple Top White Globe' Turnips

‘Purple Top White Globe’ Turnips

 

A miniature purple carrot with legs.

A miniature purple carrot with legs.

 

Two cucumbers hanging on a makeshift trellis. I can't remember what variety they are. This why I need to remember to take better notes.

Two cucumbers hanging on a makeshift trellis. I can’t remember what variety they are. This why I need to remember to take better notes.

 

'San Marzano' Roma Tomato. We grew three other varieties of tomatoes along with this one.

‘San Marzano’ Roma Tomatoes. We grew three other varieties of tomatoes along with this one.

 

The flower of a 'Hong Hong' sweet potato. We haven't harvested these yet, so we're not sure what we're going to get. Sweet potatoes are not commonly grown in southern Idaho, so we're anxious to see how they do.

The flower of a ‘Hong Hong’ sweet potato. We have not harvested these yet, so we are not sure what we are going to get. Sweet potatoes are not commonly grown in southern Idaho, so we are anxious to see how they do.

 

We grew lots of flowers, too. 'Black Knight' scabiosa (aka pincushion flower)was one of our favorites.

We grew lots of flowers, too. ‘Black Knight’ scabiosa (aka pincushion flower) was one of our favorites.

 

Some flower's we grew specifically for the bees, like this bee's friend (Phacelia hastate).

We grew some flowers specifically for the bees, like this bee’s friend (Phacelia tanacetifolia).

 

We grew other flowers for eating, like this nasturtium.

We grew other flowers for eating, like this nasturtium.

 

Even the cat loves being in the garden...

Even the cat loves being in the garden…

It has been an incredible year. “Abundant” is the best word that I can think of to describe it. We have learned a lot through successes and failures alike, and we are anxious to do it all again (and more) next year. Until then we are getting ready to settle in for the winter – to give ourselves and our garden a much needed rest. For more pictures and semi-regular updates on how our garden is growing, follow Awkward Botany on tumblr and twitter, and feel free to share your gardening adventures in the comments section below.

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Drought Tolerant Plants: Blue Sage

If you are considering installing a drought tolerant garden on your property or including more drought tolerant plants in your landscape, one plant that should come standard is blue sage. Its silvery-green foliage, large, abundant, purple-blue flower stalks, and attractive mounded shape, make it an excellent feature in any water-efficient garden bed.

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Salvia pachyphylla is in the mint family (Lamiaceae). It has several common names which it shares with several other plants: blue sage, Mojave sage, rose sage, mountain desert sage, giant-flower sage. For this post we will refer to it as blue sage; however, if you’re looking to purchase it, make sure to verify the botanical name. Blue sage is a subshrub that can grow up to 3 feet tall and 3 feet wide. It tends to remain smaller – around 1-2 feet tall – in its native habitat. It is found in the southwestern states of the United Sates on dry, rocky slopes and flats at elevations between 5,000 – 10,000 feet. The leaves are oppositely arranged and covered with fine hairs that lay tightly against the leaf surface giving the foliage its silvery appearance. Like all other sages, the leaves of blue sage are highly aromatic.

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The flowers appear in compact clusters on spikes that extend upward from the branches. The inflorescences can be several inches long. They have numerous large, purple bracts that appear in a whorled pattern along the spike. The violet-blue flowers are small but prolific and appear between the bracts surrounding the stalk. Flowering occurs throughout the summer (July-September in its native range). The flowers attract droves of pollinators including bees, butterflies, and hummingbirds. Blue sage is especially beneficial to native pollinators. In fact, while taking photos for this post, I noted that the flowers were being visited by several bumblebees. Its benefit to pollinators is another great reason to include this plant in your landscape.

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Blue sage is a very drought tolerant plant. Once it is established it requires only occasional watering throughout the summer in order to keep it looking good. It performs well in a variety of soil types, but like most drought tolerant plants it is best placed in well drained soil. Heavy soils can be amended by mixing in things like sand, lava rock fines, and compost at planting time. It prefers full sun and is winter hardy to USDA hardiness zone 5, especially if planted in an area where the soil is relatively dry throughout the winter. Blue sage is a long lived plant and can be kept in shape by cutting back the spent flowers in the fall. The folks at Plant Select recommend planting blue sage with, among other things, penstemon, coreopsis, and creeping veronica.

Photos were taken at Idaho Botanical Garden in Boise, Idaho.

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Corpse Flower Blooms Again

It is not often that a plant in bloom makes headlines, but that is precisely what happened last week when another corpse flower bloomed at Missouri Botanical Garden. Amorphophallus titanum, commonly known as titan arum or corpse flower, is a rare species, both in cultivation and in the wild. It also rarely flowers, and when it does, the bloom only lasts for a few short days. It has the largest known unbranched inflorescence, and its flowers give off the scent of rotting flesh. For all these reasons, it is understandable why a blooming corpse flower might make the news.

Titan arums naturally occur in the western portion of an Indonesian island called Sumatra. Their future is threatened because they occur in rainforests that are currently being deforested for timber and palm oil production. Deforestation is also threatening the survival of the rhinoceros hornbill, a bird that is an important seed distributor of titan arums. Today there are a few hundred titan arums in cultivation in botanical gardens throughout the world. They are a difficult species to cultivate, but their presence in botanical gardens is important in order to learn more about them and to help educate the public about conservation efforts.

Amorphophaulls titanium, titan arum (photo credit: eol.org)

(photo credit: eol.org)

Titan arums are in the arum family (Araceae), a family that consists of around 107 genera including Caladium (elephant ears), Arisaema (jack-in-the-pulpits), and Wolffia (duckweeds), a genus that wins the records for smallest flowering plant and smallest fruit. Titan arums are famous for their giant inflorescence, which can reach more than 10 feet tall. The flowering stalk is known botanically as a spadix, a fleshy stem in the shape of a spike that is covered with small flowers. The spadix of titan arums are wrapped with a leaf-like sheath called a spathe. Upon blooming, the temperature inside the spathe rises and the flowers begin to release a very foul odor, similar to the smell of rotting flesh. This attracts pollinating insects such as carrion beetles, sweat bees, and flesh flies, which get trapped inside the sheath and covered with pollen. After a few hours the top of the spadix begins to wither, allowing the insects to escape, off to pollinate a neighboring corpse flower [the spadix includes male and female flowers, which mature at different times in order to prevent self-pollination]. Once pollinated, the flowers begin to form small red fruits which are eaten by birds. The seeds are then dispersed in their droppings.

The large, stinky inflorescence is not the only structure that gives titan arums their fame. They are also known for their massive single leaf, which can reach up to 20 feet tall and 15 feet wide, the size of a large shrub or small tree. All of this growth is produced from an enormous underground storage organ called a corm. The corms of mature titan arums typically weigh more than 100 pounds, with some known to weigh more than 200 pounds. Titan arums bloom only after the corms have reached a mature size, which takes from seven to ten years. After that they bloom about once a year or once every other year, depending on when the corm has accumulated enough nutrients to support the giant flowering structure.

Below are two time lapse videos of titan arums in bloom. The first is from Missouri Botanical Garden, and the second is from United States Botanic Garden.

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Ground Nesting Bees in the Garden

Earlier this year I wrote about planting for pollinators. In that post I briefly introduced various things that people can do to encourage pollinator activity in their yards and gardens. One thing that I mentioned was the importance of providing nesting sites. Most pollinators are insects and insects are small, so the distance that they are able to travel in search of food is relatively limited. According to the Xerces Society, the smallest bees can only fly a few hundred feet from their nests. Providing nesting sites in close proximity to foraging sites is incredibly important.

Roughly 70% of native bee species in North America are ground nesting bees, so chances are pretty good that if you are providing forage for bees in your yard, a good number of the bees that visit will be ground nesting bees. In order to ensure the survival of these bees, consider providing nesting habitat for them on your property.

ground nesting bee_lasioglossum

Lasioglossum leucozonium – a North American ground nesting bee (also known as a sweat bee) – photo credit: www.eol.org

Here are a few things to keep in mind when developing nesting habitat for ground nesting bees:

Create and Maintain Undisturbed Bare Ground: You may already have ground nesting bees living in your yard and you don’t even know it. Obvious evidence of nests is difficult to spot. If you can find tunnel entrances, they will look like small ant mounds. If you find a series of small “ant mounds”, watch for bee activity during sunny times of the day. Activity can be quite ephemeral though, so it is difficult to know if bees have just moved in or if they have moved on. Avoid tilling up soil and walking through areas where you suspect or intend for bee activity. Leave patches of bare ground unplanted and unmulched in order to encourage bees to nest there.

Sunny and South Facing: Bees are most active when the sun is shining and temperatures are warm. For this reason they tend to build their nests in warm, sunny spots. However, warm, sunny spots are also the best locations for many plants. Consider sharing these sites with ground nesting bees. Avoid putting down mulch in these areas and keep vegetation sparse and minimal.

Avoid Pesticides: When encouraging pollinator activity in your yard and garden, it is best to avoid using pesticides as much as possible. Herbicides kill potential food sources. Insecticides can kill pollinating insects along with pest insects. And soil fumigants can harm ground nesting bees.

Provide Some Accommodations: Due to the diversity of ground nesting bees, it is difficult to provide nesting habitat for all potential species. Some prefer loose, sandy soil while others prefer smooth, packed ground. Some bees will nest on level ground, while others prefer sloped ground. The habitat you are able to provide will depend on the conditions present on your property. Some modifications can be made, but this all depends on the resources available to you and how particular you want to get. Apart from maintaining a patch of undisturbed, unmulched, south facing ground, there are three additional things that you can offer ground nesting bees to make them feel more at home on your property: food (in the form of diverse flowers blooming throughout the growing season), a water source (in the form of a birdbath or something similar), and a few rocks for the bees to perch on and warm their tiny bodies.

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The tunnel entrance of a ground nesting bee.

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Tunnel entrances are often found in groups in areas of bare ground mixed with patchy vegetation.

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Planting for Pollinators

“All urban greenspaces offer potential for pollinators, and all can become important links in a chain of wildlife habitat winding through developed land. At the most basic level, healthy greenspaces mean healthy people and healthy communities. And at the core of a healthy environment are the pollinators.” –excerpt from the book, Attracting Native Pollinators by The Xerces Society

Concern for pollinators, particularly bees, is widespread. Whether you pay attention to the news or not, you are most likely aware that something is up. The bees are disappearing and no one seems to know why. Of course, most of the news concerning dying bees is in reference to honey bees, largely because they are major agricultural pollinators and producers of honey. But there are two things that many people may not be aware of: 1. Honey bees are not native to North America – they were brought over from Europe by early settlers – and 2. North America is replete with native pollinators (including numerous species of bees, butterflies, beetles, and wasps) and they, too, are threatened (partly due to non-native honey bees, but we won’t get into that here). Oh, and there is a third thing, we do know why bees and other pollinators are disappearing, and it’s not because of cell phone towers or other wacky ideas that have been proposed.

Actually, pollinator decline is due to a whole suite of things. As much as we like to seek out the silver bullet – the single cause with a single solution that will solve the problem – this issue (like so many others) does not have one. Habitat degradation and loss, the spread of pests and diseases, extensive pesticide use, and climate change all play a role in pollinator decline. Consider a modern day farm: acres and acres of a single crop planted from one edge of the field to the other, often planted with an herbicide resistant variety of crop so that all plants (both weedy and non-weedy) can be sprayed and killed leaving only the crop in question to grow competitor free. Or consider an urban landscape: patchy green space amidst miles and miles of pavement, concrete, and rooftops, and when that green space occurs, it is often a chemical green lawn free of weeds or a flower bed loaded with non-native ornamentals, bred for aesthetic appeal and often lacking in wildlife value. Our modern landscapes just aren’t fit for pollinators.

But things can change. The problem is complex, but there are small things each of us can do that when added up can make a colossal difference. Creating pollinator friendly habitats in our communities – spaces that are free from pesticides and include diverse food sources and nesting sites – can help ensure that pollinators will survive and thrive. Here are a few guidelines and resources to help you create pollinator habitat in your yard or neighborhood:

– Find a sunny location: Pollinators are most active when it is warm, so find areas that get at least 6-8 hours of full sun (just like you would if you were planning a vegetable garden).

– Plant a wide variety of plants: Something should always be in bloom during the growing season, so select at least 3 plants that flower in each of the 3 blooming periods (spring, summer, and fall). Early spring bloomers and fall bloomers are especially important. Also, in order to attract a wide range of pollinators, select plants with varying heights and growth habits and that have flowers of various colors, shapes, and sizes.

– Plant in clusters: On each foraging trip, bees visit the flowers of a single plant species, so plant each species in small clumps.

-Provide nesting sites and a water source: Bumble bees nest at the bases of bunchgrasses, so include a warm season bunchgrass like little bluestem in your yard. Ground nesting bees require a section of bare ground, so lay off on the mulch. Construct and install bundles of hollow stems (like bamboo or elderberry) in order to provide nesting sites for mason bees. Also, include a birdbath or something with a ledge for pollinators to perch and drink.

There are many resources that can instruct you on providing habitat for pollinators. One standout is The Xerces Society. They are “a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat.” Their website is loaded with information: specific plant recommendations by region, instructions on how to provide habitat for certain pollinators, alternatives to pesticides, etc. You can even help them by becoming a citizen scientist. Other excellent resources include Monarch Watch and The Great Sunflower Project.

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“Simple decisions about selecting plants, providing nest sites, minimizing disturbance, and reducing pesticides can make a dramatic difference between a green, manicured, but lifeless landscape, and one that teems with the color, energy, and life of buzz-pollinating bumble bees, rapidly dashing hummingbird moths, and busy nest-building leafcutter bees.” –excerpt from Attracting Native Pollinators by The Xerces Society

Stay tuned for future posts about pollinators, including pollinator conservation and specific pollinator and plant interactions. Also, comment below to share what you are doing to help pollinators in your community. 

Related Posts:

–In the News: Declining Insect Populations

–Figs and Fig Wasps