14 Botanical Terms for Flower Anatomy

I like to know the names of things. Certainly I don’t have to know what everything is called in order to appreciate it for what it is, but that appreciation deepens when I understand it better. Scientific exploration helps us discover the workings of the world around us, and through that exploration comes the naming and describing of things. The names are largely arbitrary apart from the fact that they help us keep track of the descriptions associated with the discoveries. Calling things by name and knowing how to describe them not only increases our awareness of the natural world but can also give us greater appreciation for the larger picture and our place in it all. With that I introduce a new series of posts concerning botanical terms.

It’s mid-summer now (at least in the northern hemisphere) and flowers abound, so this first Botanical Terms post will help us become better familiar with flower anatomy. [I'm also releasing this post while the Botanical Society of America convenes for its annual conference in my current hometown - Boise, Idaho - so it seems fitting]. Of course, as soon as I began looking into the subject of flower anatomy, I realized very quickly that, like so many other things, it is incredibly complex. First of all, in the larger world of plants, not all produce flowers. Non-vascular plants don’t. And within the category of vascular plants, non-seed producing plants don’t make flowers either. Within the category of seed producing plants, there are two groups: gymnosperms and angiosperms. Angiosperms produce flowers; gymnosperms don’t. Even though that narrows it down quite a bit, we are still dealing with a very large group of plants.

The complexity doesn’t stop there, of course. Memorizing the names of flower structures and recognizing them on each flowering plant would be easy if every flowering plant had all of the same structures and if all structures existed on each flower. However, this is not the case. Depending on the flower you are looking at, some structures may be absent and some may have additional structures that are not common ones. Also, some plants have inflorescences that appear as a single flower but are actually a collection of many smaller flowers (or florets), like plants in the sunflower family (Asteraceae) for example. Regardless, we are going to start with basic terms, as there are a large number of flowering plants that do exhibit  all or most of the following basic structures in their flowers.

flower anatomy

Pedicel and Peduncle: These terms refer to the stem or stalk of the flower. Each individual flower has a pedicel. When flowers appear in groups (also known as an inflorescence), the stalk leading up to the group of flowers is called a peduncle.

Sepal and Calyx: Sepals are the first of the four floral appendages. They are modified leaves at the base of the flower that protect the flower bud. They are typically green but can be other colors as well. In some cases they may be very small or absent altogether. The sepals are known collectively as the calyx.

Petal and Corolla: Petals are colorful leaf-like appendages and the most familiar part of a flower. They come in myriad sizes, shapes, and colors and are often multi-colored. Their purpose is to attract pollinators. Many plants are pollinated by specific pollinators, and so their petals are designed to attract those pollinators. The petals are known collectively as the corolla.  

Stamen, Anther, and Filament: Pollen is produced in a structure called an anther which sits atop a filament. Collectively this is known as a stamen. Stamens are considered the male portion of the flower because they produce the pollen grains that fertilize the egg to form a seed. Flowers often have several stamens, and on flowers that have both male and female structures, the stamens are found surrounding the female portion.

Pistil, Carpel, Stigma, Style, and Ovary: The female portion of a flower consists of a stigma (where pollen grains are collected), a style (which raises the stigma up to catch the pollen), and an ovary (where pollen is introduced to the ovules for fertilization). Together this is known as a carpel. A collection of carpels fused together is called a pistil. Just like with stamens, flowers can have multiple pistils.

Start learning to identify floral structures on flowers like rugosa rose (Rosa rugosa). (photo credit: eol.org)

Start learning floral anatomy on flowers with easily recognizable structures like the flowers of rugosa rose (Rosa rugosa). (photo credit: eol.org)

Flowers are small art pieces, worthy of admiration in their own right. However, recognizing and exploring the different floral structures can be just as enthralling. The structures vary considerably from species to species, each its own piece of nature’s artwork. So, I encourage you to find a hand lens (or better yet a dissecting microscope) and explore the intimate parts of the flowers around you.

Feeding the World with Microbes

Back in the mid 1900’s, after the tragic days of the Dust Bowl in North America, new agricultural techniques and technologies were developed and distributed in the name of food security. These developments included higher yielding plant varieties, synthetic fertilizers and pesticides, and advancements in irrigation and other management practices. This period in time was termed the Green Revolution, and it truly was a remarkable time. Agricultural advancements that came out of this period have helped us feed the world and stave of starvation for millions of people. Today, issues of hunger and starvation are political problems, not necessarily agricultural ones. However, the human population continues to grow, and today’s 7 billion people is projected to reach up to 10 billion (or more) in the coming decades. The world’s best farmland is either already in use, degraded, or being used for other things. This means that we must find a way to feed a growing population with the diminishing farmland that is available. We may be producing enough food now (despite the distribution problem), but will we be able to produce enough in the future? The hunt for the Green Revolution 2.0 is on.

“According to the [UN's Food and Agriculture Organization], most of the growth in production…has to come from increasing yields from crops. Selective breeding doesn’t seem to be offering the types of dramatic yield increases seen in the past. Meanwhile, genetic engineering has yet to lead to any significant increase in yields. Now, many scientists are saying that we’ve been looking at the wrong set of genes.”

These are the words of Cynthia Graber, author of an article that appeared last month on PBS Online’s NOVANext entitled, “The Next Green Revolution May Rely on Microbes.” In it she explores the argument that increasing future yields will depend on better understanding the soil’s microbial community and its complex interaction with the plant community. The big question: if microbes can be artificially bred – the same way virtually all agricultural plants have been – might they help us increase food production?

Microbial life in the soil is incredibly diverse. In one teaspoon of soil, there can be billions of individual microbes including bacteria, fungi, protozoa, algae, and nematodes. Our current understanding of soil life is extremely limited, akin to our understanding of outer space and the depths of the oceans. That is because, as stated in Graber’s article, “perhaps 1% of all soil microbes can be grown in a petri dish, the conventional model for such research.” This limits our ability to study soil microbes and their interactions with other living things. We do, however, acknowledge that the interactions between the roots of plants and soil microbes is incredibly important.

Fruiting Body of an Ectomycorrhizal Fungus (photo credit: eol.org)

Fruiting Body of an Ectomycorrhizal Fungus (photo credit: eol.org)

One major player in these interactions is a group of fungi called mycorrhizae. “Mycorrhizal fungi cannot survive without plants, and most plants cannot thrive without mycorrhizal fungi.” It is a symbiotic relationship, in which the fungi offer plants greater access to water and nutrients, and plants feed sugars derived from photosynthesis to fungi. Recent advancements in genetics have allowed researchers to better analyze the genes in microbes like mychorrizal fungi and determine the functions of them. Through selective breeding, microbes can be produced that will offer even greater benefits to plants, thereby increasing yields. For example, some microbes help plants tolerate heat and drought. Isolating the genes that give microbes these abilities, and then breeding these genes into other microbes might allow for a wider palette of plants to receive this kind of assistance.

In researching this article, Graber followed a Swiss researcher to Colombia where he was testing lines of mychorrhizal fungi on cassava. The fungi were specifically selected to increase a plant’s access to phosphorous. This is one of many experiments that are now under way or in the works looking at specially bred microbes in agricultural production. It’s an exciting new movement, and rather than spoil too much more of Graber’s article, I implore you to read it for yourself. Share any comments you may have in the comment section below, and expect more posts about plant and microbe interactions in the future.

Cynthia Graber appeared at the beginning of a recent episode of Inquiring Minds podcast to talk about her article. I recommend listening to that as well.

Hundreds of Japanese Plants Threatened with Extinction

Life has existed on earth for at least 3.5 billion years, and during that time there have been five mass extinctions. Currently, we are in the middle of a sixth one. The major difference between the current extinction event and others is that this one is largely human caused, which is pretty upsetting. However, knowing that detail has its upside: if humans are the drivers of this phenomenon, we can also be the ones to put on the brakes.

Biologists have spent the last several decades tracking the current mass extinction, endeavoring to come up with a list of species that have the greatest risks of extinction, as well as lists of species that are at less of a risk, etc. The problem is that factors leading up to extinctions are diverse, and available data for making predictions is lacking, especially temporal data. Recognizing this information gap, researchers in Japan set out to better determine the extinction risk of Japanese flora. Using data from surveys done by lay botanists in 1994-95 and 2003-04, they were able to calculate a trend which indicated that, under current circumstances, between 370 and 561 plant species in Japan will go extinct within the next 100 years.

photo credit: wikimedia commons

photo credit: wikimedia commons

The methods for this study, as described in the findings which appeared last month in PLOS ONE, involved dividing Japan into 3574 sections measuring around 100 square kilometers each and covering about 80% of the country. More than 500 lay botanists tallied the numbers of species that were found in each section during the two time periods. 1735 taxa were recorded, and out of those, 1618 were considered quantifiable and used in the analysis.

Japan is home to a recorded 7087 vascular plant taxa. Historically, the extinction rate of plant taxa in Japan has been around 0.01% per year. According to this study, over the next 100 years the extinction rate will rise to between 0.05 and 0.08% per year. Researchers are organizing a third census in the near future in order to monitor the actual extinction rate and better determine the accuracy of this prediction.

Data collected in these censuses was also used to evaluate the effectiveness of protected areas and determine the need for improvements and expansions. Natural parks cover 14.3% of Japan, but only about half of that area is regulated for biodiversity conservation. The researchers found that protected areas do help to reduce the risk of extinctions, but that their effectiveness is far from optimum and that even expanding protected areas to cover at least 17% of the nation (a target set at the recent Convention on Biological Diversity) would not effectively gaurd threatened plant species from extinction.

In their conclusion, the researchers advise not only to expand protected areas but to improve the “conservation effectiveness” of them, and “to improve the effectiveness of them, we need to know the types of pressures causing population decline in the areas.” They go on to list a few of these pressures, including land development and recreational overuse, and suggest that management schemes should be developed to focus on specific pressures.

Japanese Primrose, Primula japonica (photo credit: eol.org)

Japanese Primrose, Primula japonica (photo credit: eol.org)

One thing I found very interesting and encouraging about this study was the recruitment of lay botanists in collecting data. As stated in the findings, “Monitoring data collected by the public can play an essential role in assessing biodiversity.” I am excited by the growing citizen science movement and hope to see it continue to expand as more and more people become interested in science and eager to add to this body of knowledge. In fact, I consider the term “awkward botany” to be synonymous with citizen, lay, and amateur botany. That is precisely why I chose it as the title for my blog. So, in short, expect more posts involving citizen science in the future.

You can read more about this study on John Platt’s blog Extinction Countdown at Scientific American.

 

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 oder, 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 know 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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Wildflower Walk: June 2014

I spent last weekend in a cabin outside of Garden Valley, Idaho. I was there for a wedding and so most of my time was occupied with that. However, anxious to explore, I found a brief moment to step out and observe the surrounding plant life. The cabin and an adjacent campground were located in an area that, before the economic downturn in 2008, was to become a major housing development. Because of this (and possibly other things), the area showed lots of signs of human disturbance, particularly the large number of introduced plant species. Fortunately, despite feeling like I was walking through a weedy field, I did come across a few patches of native plants. I may have to return sometime to get a better look at things because I wasn’t able to identify everything that I saw and I’m still not exactly sure what species of lupine and buckwheat I was looking at. Either way, the plants in the following pictures are a few of the things I found.

Aristida purpurea (purple threeawn)

lupinus

Lupinus sp. (lupine)

eriogonum

Eriogonum sp. (wild buckwheat)

amelancier alnifolia

Amelanchier alnifolia (Saskatoon serviceberry)

Don’t let my walk through a weedy field dissuade you. Garden Valley is an incredibly beautiful location. It sits adjacent to the South Fork of the Payette River and near the western edge of the Boise National Forest. It is an area worthy of exploring, which is why I plan on visiting again soon. I recommend you do too.

Previous Wildflower Walks:

-Spring 2013

-June 2013

-American Penstemon Society Field Trip

-September 2013

Ethnobotany: Marigolds

Marigolds are easily one of the most commonly grown annual flowers. They are so common and pervasive, in fact, that they are often overlooked and underappreciated. I, for one, had discounted marigolds long ago, seeking instead for plants considered to be more rare, unconventional, and unusual to place in my garden. But then I started looking into this commonplace plant and, to my surprise, discovered that marigolds have great cultural significance in countries all around the world, both currently and historically. Suddenly, marigolds don’t seem quite so ordinary.

Marigold is a common name for plants found in several genera, but in this case I am referring to plants in the genus, Tagetes, which is in the family, Asteraceae (also known as the sunflower family). Tagetes is a genus composed of at least 42 species, all of which are native to North and South America. Plants in this genus range in height from a few inches to as tall as 6 feet or more. Like most other species in the sunflower family, their flowers appear to be single blooms but are actually clusters of two different types of smaller flowers: ray florets and disc florets. The flowers can be orange, yellow, golden, white, and, in some cases, maroon or with maroon accents. The leaves are usually finely divided and either oppositely or alternately arranged, and the leaves, stems, and flowers are highly aromatic. Marigolds grow in a variety of soil types, even those with minimal fertility. In gardens, they will perform best if they are grown in well-drained soil in full sun and are watered and deadheaded regularly.

Aztec Marigold (Tagetes erecta)

Aztec Marigold (Tagetes erecta)

Even before marigolds gained worldwide popularity, they were commonly used among the people in their native range. They were of particular interest to the Aztecs, who considered marigolds a sacred plant and used them in religious ceremonies. Marigolds became known as the flower of the dead and are still used today during the Day of the Dead to adorn altars and graves. Marigolds were also an important medicinal plant for the Aztecs, especiallly T. lucida, which they used to treat fevers, stiffness, blisters, and various other ailments.

Spanish and Portugeuse explorers were introduced to marigolds by the Aztec people. The explorers brought marigolds back to their homelands and quickly spread them throughout Europe and into Africa and Asia. It was in Europe that they were given their common name, Mary’s gold, referring to the Virgin Mary and the color of the flowers.  At the beginning of the 16th century, Portuguese explorers established a colony in India. The marigolds they brought with them have become a huge part of Indian culture and other cultures in that region. Today there are many large marigold farms in various parts of India, and marigolds are used widely to make garlands and other decorations for weddings, festivals, and religious ceremonies, as well as in foods and dyes.

Marigold Garlands (photo credit: wikimedia commons)

Marigold Garlands (photo credit: wikimedia commons)

The flowers and leaves of marigolds are edible and have culinary and medicinal uses in many countries, especially those in South America. T. lucida and T. minuta are particularly popular for these uses. Marigold flowers have a citrus-like flavor, and T. tenufolia ‘Lemon Gem’ is said to be the best tasting marigold (although, having never eaten marigold flowers myself, I have no personal experience to back that up). The essential oil of T. minuta is frequently used in the fragrance industry and as a medicinal oil. However, T. minuta has also become naturalized in many parts of the world, including Africa, Asia, and North America, and is considered an invasive weed species in these areas.

Marigolds are often planted in vegetable gardens because they are assumed to repel pest insects and/or attract beneficial insects. Little research has been done to back up these claims. The one thing that I was able to confirm is that they have been found to reduce populations of nematodes in the soil. However, just interplanting marigolds among vegetable plants is not enough; instead, a large number of marigolds would need to be planted and then tilled into the soil in order to have the desired effect. Surely marigolds attract pollinating insects, but do they repel pests (apart from nematodes) or attract other beneficial insects?  If you have an answer to this, comment below.

Tagetes minuta (photo credit: eol.org)

Tagetes minuta (photo credit: eol.org)

I have marigolds in my garden this year, partly due to my newfound appreciation of them. If you’d like to see pictures of my marigolds, along with pictures of other things I’m growing, seeing, and doing, subscribe to my tumblr and/or follow me on twitter.

Urban Trees: Unlikely Polluters

Trees are central features in urban environments, and their benefits are numerous and well documented. They give off oxygen and sequester carbon, provide food for urban wildlife, help slow storm water runoff, and provide shade which not only keeps us cool in the hot sun but can help increase the energy efficiency of surrounding buildings. And even if they weren’t doing all these things and more, the aesthetic value they add to our concrete jungles alone is worth having them around. So it is a little disconcerting to learn that the trees we benefit so much from may actually be doing us harm by way of increasing levels of air pollution.

It sounds unlikely, but according to researchers at the Institute for Advanced Sustainability Studies in Postdam, Germany, urban trees can contribute to increased levels of tropospheric ozone, a key component of smog. This occurs when trees emit volatile organic compounds (VOCs), special gasses that are meant to attract pollinators, repel insects, and warn nearby trees of ensuing insect herbivory. These biogenic VOCs react with sunlight and nitrogen oxides (another key component of smog and a result of burning fossil fuels) and form ozone. Ozone in high concentrations is particularly harmful to the lungs, aggravating asthma, increasing susceptibility to lung infections, and damaging the lining of the lungs.

Fortunately, according to the study, certain trees contribute significantly less to ozone production than other trees.  Poplars, oaks, and willows, for example, tend to be high emitters of VOCs, whereas birches and lindens emit much less. Planting low VOC emitters in dense urban areas and keeping high VOC emitters scattered throughout the city instead of planted in large groups will help reduce this phenomenon. A recent article at Scientific American points out that cities that are sunnier and warmer have more to worry about than cloudy and cool cities since sunlight and high temperatures speed up the ozone producing reaction.

Despite this unfortunate discovery, trees still have an important role in cities. Apart from placing and planting the proper trees, our focus should be on finding ways to reduce our fossil fuel emissions which remain the major culprit of our polluted air.

River birch (Betula nigra) - Birches were found to low emitters of volatile organic compounds compared to other common urban trees

River birch (Betula nigra) – Birches were found to be low emitters of volatile organic compounds compared to other common urban trees (photo credit: wikimedia commons)