Sunday, April 29, 2012

Florida’s Mangroves: A Cross-family Comparison

By Lily Everson and Kara Cecil

This post is one of a series from professor Nisse Goldberg's Plant Taxonomy students at Jacksonville University. FNPS blogger Laurie Sheldon assisted the students with their initial drafts, providing suggestions for editing and content development.

Mangroves are tropical trees that can grow well in both fresh and brackish water. There are four main species of mangroves in Florida: the red mangrove (Rhizophora mangle, Fig. 2), the black mangrove (Avicennia germinans, Fig. 3), the white mangrove (Laguncularia racemosa, Fig. 4), and buttonwood (Conocarpus erectus). This article will focus on the red, black, and white mangrove species.

Figure 1. Mangrove zonation.
Mangroves are traditionally found on the coasts of Florida as far north as St. Augustine. With the warming of temperatures, the mangroves have been spreading northward into salt marsh habitats dominated by Spartina alterniflora. This has become a topic of interest due to the ecological consequences of such a major habitat shift.

The red mangrove, a member of the Rhizophoraceae family, is common to Florida’s coastal peninsula.  This family of mangroves dominates the waterline of Florida’s southern estuaries (Fig. 1) and is easily identified by its prop roots (Fig. 2), big shiny leaves, and long, pencil-like fruits, which can be seen floating in the water.

The family that the black mangrove (Fig. 3) belongs to is actually up for debate. Some consider it a member of the Avicenniaceae, Acanthaceae, or even the Verbenaceae. It is found further up in the intertidal zone, and between the bands of red and white mangroves (Fig. 1). The black mangrove has narrow, elliptical leaves that are typically encrusted with salt. Their cable-like roots radiate out from the tree and have finger-like projections or pneumatophores that extend out the soil.  These structures are used to provide oxygen to the roots.

The white mangrove (Fig. 4), a part of the Combretaceae family, dominates the upper intertidal zone along the coasts of Florida (Fig. 1). It has oval-shaped leaves that appear silvery with a green-yellow tint. The nectary glands are found on the stem at the base of the leaf and are used by the plant to attract ants, which in turn protect the plant from herbivorous insects.

Figure 5.  Mangrove propagules. Photo credit:
Marine Resources Council of East Florida.
Mangroves spread their offspring as propagules (Fig. 5). The propagules mature on the parent plant and then float with the currents before they settle. They each require a certain amount of time floating in the water before they can successfully take root. Look for the propagules that may wash up on your beach! 

Florida State Law protects mangroves as they help prevent erosion of our beaches by stabilizing the sand and dampening the impact of waves. They are also very important to the food chain because they are a major habitat source for juveniles of many species.

Judd, WS, Campbell, SC, Kellogg, EA, Stevens, PF, and Donoghue, ML. 2008. Plant systematics: A phylogenetic approach. Sinauer Associates, Inc. Massachusetts, USA.  

Image Sources
Figure 4.
Figure 1.
Figure 2.
Figure 3.
Figure 5.

Thursday, April 26, 2012

An Ode to Volunteers

By Cindy Liberton, 32nd Annual FNPS Conference Planning Committee

Corridor Expedition route
Here we are again, between Earth Day 2012 and Arbor Day, holidays best spent outdoors.

Earth Day was originally intended as a date to commemorate humankind's relationship with the planet. Since its start in 1970, we have seen the event evolve, wax and wane, but, to me, April 22nd means a day for celebration, reflection, and lots of community events.  Each event, in every, community, wouldn't happen without volunteers.  And that is a big thing, and something to reflect upon.

2012’s Earth Day in Florida was especially remarkable to me because of some specific volunteers, both renowned and unsung. On this Earth Day, just over the Florida state line, four intrepid environmentalists completed day 97 of the "1000 miles, 100 Days”  Florida Wildlife Corridor Expedition . Their efforts to spotlight the remaining greenways and wildlife corridors of Florida have made the news throughout the state. Jeff Klinkenberg covers their journey in an article published on Earth Day in the Tampa Bay Times. 

Speaking of Jeff Klinkenberg, he will help us welcome the attendees to the 32nd Annual Florida Native Plant Society Conference on the morning of May 18. I highly recommend reading his anthologies (Pilgrim in the Land of Alligators, Seasons of Real Florida). The conference planning team (all volunteers... we'll get to that) invited Klinkenberg to our conference because of his favorite subject matter: People who make a Difference in Florida.

All of the Florida Native Plant Society (FNPS) members that I know are intensely interested in making a difference... after all, they joined to support the mission of preserving, conserving and restoring native plant populations. Plants certainly don't speak for themselves, always taking back stage to the charismatic manatee, panther and bear. Citizen naturalists and scientists who are interested in native plants are united in the scary belief that if we do nothing, plant populations will continue to be bombarded by human influences; only human action can change this.

Many members of the FNPS dedicate an amazing amount of their time and talents to waving the flag for Florida's native plants. They restore damaged lands, pull bad exotic plants from trees, spend endless hours at booths, and plant demonstration gardens. They give talks to whomever will listen. Whether they study, teach, draw, or photograph, they incrementally add to all that has come before. As do those who work on the annual FNPS conference,  from different Chapters each year.

On Earth Day 2012, the day after yet another conference planning meeting in the Lutz Library, I was inspired by all the people who are donating their time, money, and lots of Saturdays to support this event. This is the 32nd annual conference, and I have a renewed appreciation for the hundreds of volunteers since the first one in 1980 who have innovated, reinvented, collaborated, argued, and fretted to bring the best possible program to the Society members who travel across the state each year to attend.

Captivated audience on a guided conference field trip

The reasons they do this seems appropriate to Earth Day musings; the volunteer planners are united in the desire to show off our planet's natural wonders—in this case, the plant life and ecosystems of a particular region of our state. The conference does this in a way that remains powerful and somewhat unique; it offers expert led field trips to actually see the plants where they live in the real world. Conference planners thoughtfully recruit just the right people to volunteer to lead these trips. In a time where knowledge of native plants is often limited to digital images, urban plantings, or the rare documentary, these are experiences to be treasured, and they are.

The same care goes into recruiting the speakers for the conference. I started this discussion with the Klinkenberg example, and I would be remiss not to mention our Keynote speaker, Doug Tallamy. Although he is not from Florida, Doug does have a real handle on what citizens can DO to increase the biodiversity of their communities. Rounding out our celebrity roster, we are all thrilled to bring Hilary Swain's perspectives to those who haven't had the pleasure of meeting her. As Archbold Biological  Station's  Executive Director, she has been an inspiration to all seeking to understand the science behind conservation, and how it intersects with human use of the lands. 

These presentations will nicely frame the key messages that the rest of the invited presenters have volunteered to share with attendees, often at significant personal expense. As has been the case in each of the 31 conferences preceding this one, established and emerging researchers will talk about plant science—after all—the Society's efforts are firmly rooted in science. Of course there will also be experts in horticulture and landscaping to enchant the gardener in all of us.

Importantly, this year, in a political and economic climate unfriendly to traditional conservation methods, yet somewhat protective as development is temporarily stalled, we have invited those who can help demystify the current reality of conservation of ecosystems in Florida. Whether the topic is coastal protection, cultivation of biomass, protection of our waters, or the policy machinations that influence all of this, we can guarantee that these talks will be evocative.

So, as I sit here on the banks of the Withlacoochee River wrapping this up on my IPad, I find myself somewhat passionate about the potential for cumulative effect from all these volunteer efforts, large and small. Each Earth Day, I try to be optimistic that we will find ways for people to reconnect to the natural world. The complexion of that connection will continue to evolve—we can capture a butterfly's flight on a smart phone, and identify it with an App — and still I hope. The volunteers I meet provide the basis of hope, and I believe whatever their skills or interests, they will continue to be relevant.

If you haven't decided whether to come to Plant City May 17-20 for the FNPS conference, "Preserving the Natural Heart of Florida," I suggest you do. Better yet, come and volunteer. Every contribution makes the experience better for all, and brings us together in a collaboration that may having lasting effects for, as Jeff Klinkenberg help coined it, the "Real Florida." See

Sunday, April 22, 2012

Harvesting & Storing Seeds

By Steven W. Woodmansee, FNPS President

Perhaps one of the biggest challenges to growing new native plant species is obtaining seeds and germplasm for them. Germplasm is a term used to describe any plant material used in propagation. It could be seeds, cuttings, air layers, or tissue (root or otherwise).  By and large, the plant nursery industry often prefers cuttings or tissue culture as they present the easiest/cheapest way to mass produce plants, as well as preserve certain plant characteristics. Seeds are generally the preferred method ecologically, as each seed will present a unique set of genetic material thereby assuring genetic diversity within a species and preventing things like artificial genetic drift (i.e. plants will no longer be selected for survivability), disease susceptibility, inbreeding, etc.

Not all plants are the same when it comes to harvesting, storing, & germinating seed/fruit. First things first, when harvesting wet or pulpy fruit, in general it is best to clean remove the flesh and have clean seeds. If you don’t have time to clean the fruit right away, store it in a lidless bucket with some water for less than 24 hours (Figure 1). If you need more time place them on some netting in the sun so that the flesh may dry out. It is okay if ants eat the flesh off the fruits for you. Then you can soak the fruit in a bucket for 24 hours or less and clean them. You may need to cover the bucket/netting to prevent the birds from eating all your harvest. For plants with very small seed (e.g. Corkystem passionflower, Ficus spp., or blueberries), one can crush them on newspaper and let it dry out over the afternoon. Once dry, it is not necessary to painstakingly separate the seed from the dried pulp when storing them. Some plants, such as native Crotons & Heliotropes, have seed in fruit which is a capsule that dehisce (fancy botanical jargon for opening up), one can collect these fruit and place them in a paper bag in a cool dry place, under an air conditioner vent, or even in the sun (Figure 2). The capsules will pop open and eject the seeds, so it is important to keep it tightly closed. For some plants, such as many wildflowers, it is unnecessary to clean them, and they can go straight into storage containers.

Once seeds are clean, store them in paper bags, paper envelopes or glassine envelopes like the ones from the Post Office (Figure 3). If they are in a container be sure and have it ventilated at the top by placing a hole in the lid of the jar/can. Store all seed containers in a cool dry place that is well ventilated. Heat, especially moist heat, is the biggest threat to seed storage. Although there may be some exceptions such as cold storage, seeds should never be kept in sealed containers or plastic bags of any sort or they may have fungal issues and rot. For some species, the older the seed, the less likely it will germinate. 

Some other tips on seed storing:
• Temperate plant species generally have seed that store well over time, and they may need a period of cold in order to germinate (e.g. Dahoon Holly, Oaks, & blueberries).
• Tropical plant species from moist habitats (such as hardwood hammocks) and palms generally do not have seed that store well over time (e.g. Lignum vitae, capers, & strongbacks).
• Large seed, wildflower seed, and legume seed (members of the pea family) often have seed that may store for many years (e.g. Jamaican dogwood, milk peas, skyblue clustervine, & tickseed).

FNPS members John Lawson of Silent Native Nursery and Rob Campbell of Signature Palms contributed to this article.

Image sources
pepper seed extraction and soaking
paper bag drying 

paper seed envelopes
glassine envelopes

Formatted and illustrated by Laurie Sheldon.

Thursday, April 19, 2012

Plant Profile: Coral Bean, Erythrina herbacea

By Dakota Nielsen and Ciarra Slater*

This post is one of a series from professor Nisse Goldberg's Botany students at Jacksonville University.

Kingdom: Plantae
Division: Magniolophyta
Class: Magnoliopsida
Family: Fabaceae
Genus: Erythrina
Specific epithet: herbacea

Erythrina herbacea, also known as the coralbean, Cherokee bean and the cardinal spear, is a member of the Fabaceae or pea family. It is found throughout the state, growing in hardwood hammocks, open sandy woods, and even near saltwater.

The coralbean can grow to 3-4 ft tall and has prickly stems. To maximize exposure to sunlight for photosynthesis, they can change their orientation to the light, which is known as heliotropism.

The flowers are scarlet red and bloom in the months of May to June, attracting hummingbirds with sweet delicious nectar. Coralbean takes its name from the bright red seeds found inside each pod. The large seeds are eaten by birds and other animals in late summer and autumn. Not everyone responds well to consumption of these seeds. They can cause vomiting and diarrhea when eaten by humans, and have been used in Mexico to poison rats!

Interested in growing your own (and of course, being careful that children, pets, and others do not snack on the seeds)? The Florida Association of Native Nurseries can tell you where to buy coralbean in your area.


*Edited and formatted by Laurie Sheldon.

Sunday, April 15, 2012

The Evolution of a Conference Attendee

Erysimum sp., known commonly as
wallflowers, are not native to Florida
or FNPS conferences
FNPS member Janet Bowers reflects on a half decade of conferences

I joined the Florida Native Plant Society several years ago to find out where to buy native plants. I decided to go to a chapter meeting a couple years later, which truly I enjoyed. A schedule change shortly thereafter prevented me from attending other meetings. Although I received the statewide newsletters and info about the yearly conference, I was hesitant to attend since I didn’t know anyone in the organization.

Author Janisse Ray, happily signing
books after a great lecture
The first conference I attended was in Gainesville in 2007. I actually went as a vendor to volunteer at the Bok Tower plant sale table outside. The selection at the sale was incredible. Awed by the sheer volume of plants, I quickly filled my car with purchases. When I discovered that Janisse Ray was the keynote speaker, I read her books, prepared for a great talk, and was not disappointed. Her lecture was both inspiring and entertaining. I asked her to autograph my books and chatted with her for a few minutes. I would have paid the price of admission just to hear her presentation. I met many interesting people while sitting at the plant table and attended the evening socials. While they were in interesting locations, I felt a little out of place since I didn’t know many people.

Trout lilies in bloom
In 2010 the conference was in Tallahassee. I attended Saturday and Sunday but skipped the social events. I got to know many friendly people from around the state and enjoyed the various seminars. One of the highlights for me was Bailey White’s presentation, entitled The Joys and Horrors of Inheriting an Old Family Garden. I laughed so much that tears were streaming down my face. I went to an informal lunchtime meeting and learned about a massive conservation area nearby that was covered in blooming trout lilies – the pictures were incredible. Another lecture that I absolutely loved was all about Pitcher plants as art. I had already signed up for a field trip to see pitcher plants and I like to paint water colors, so I suppose that was a given.

White pitcher plant, Sarracenia leucophylla
The field trip topped off a great two days. It was like rediscovering Florida’s wild side. Our easy walk was led by knowledgeable people eager to answer questions and share their passion for the subject. Of all the native plants we saw, the grassy orchids and pitcher plants were definitely the showstoppers. Seeing the pitcher plants made the trip to Tallahassee worthwhile and the cost of the field trip a bargain! I volunteered to drive and, as luck would have it, one of my riders was the co-author of a great Appalachian wildflower reference book. You never know who you will meet! I surely made friends at this conference. As an added bonus, there were a wide variety of vendors (from T-shirts and note cards to wild flower seeds) and a silent auction with one-of-a-kind items, for which the proceeds benefit FNPS.

Disney Wilderness Preserve
The Maitland 2011 conference featured some great speakers and field trips. I went on the Disney Wilderness Preserve hike and saw several plants I’d never seen before, in addition to jumbo bee nest high in a tree. I bought some native milkweeds and a few other plants that are quite happy in my yard.

Welcome to Plant City!
The 2012 conference will be about 5 miles from my house so I plan to volunteer for most of it. I am very excited to be welcoming native plant lovers to Plant City. The field trip lineup is excellent and the socials look great. A special homeowner workshop will take place on Saturday afternoon. Let your friends know that for $25 they can learn a ton about natives and purchase them all in the same place.

Please come and join us - there will be something for everyone!

Hoping to see you there,
Janet Bowers

Image sources, in order of their appearance:
Janisse Ray
Trout lilies
White pitcher plant
Disney Wilderness Preserve
Plant City Water Tower

Editing, formatting, and photo representation by Laurie Sheldon

Thursday, April 12, 2012

Cuscuta pentagona: The "Dodder" That Won't Leave Home

By Jeff Cassel

This post is one of a series from professor Nisse Goldberg's Plant Taxonomy students at Jacksonville University.
Figure 1: Dodder stems lack chlorophyll and are easy to spot because of
their orange color. Photo credit: Curtis Clark.
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Solanales
Family: Cuscutacea
Genus: Cuscuta
Specific epithet: pentagona
Common name: Fiveangled Dodder

Figure 2: White, bell-shaped dodder flowers. Photo credit: Curtis Clark.
Cuscuta pentagona, or fiveangled dodder is a parasitic climbing vine, which means that it derives its nutrients from other organisms. Fiveangled dodder can be found throughout Florida in a variety of different habitats that include hammocks, dunes, and brackish marshes. You can recognize the plant by its yellow to orange stems (Fig. 1) and white, bell-shaped flowers (Fig. 2).

Because it is parasitic, dodder does not have chlorophyll and therefore does not photosynthesize. Dodder produces large numbers of seeds that depend on weathering or fungal attacks in order to germinate. These seeds can live in the soil for up to 20 years, waiting for the perfect conditions. Once a seed germinates, the growing plant must reach a host within a few days or die. When dodder attaches to a host, it pierces through the host's epidermis or ‘skin’ layer in order to extract nutrients. Dodder is dependent on the host for survival, so it usually does not kill its host. However it does weaken the host, making it subject to diseases.

The fiveangled dodder has been used by the indigenous peoples as a laxative, contraceptive, and even to treat tuberculosis!

Wunderlin, RP and Hansen, BF. 1998. Guide to the Vascular Plants of Florida. Gainesville: University of Florida.

Image Sources
Figure 1: Dodder stems
Figure 2: Dodder flowers

Edited and formatted by Laurie Sheldon

Sunday, April 8, 2012

Plant City: History in the Heart of Florida

by Cindy Liberton

Location, Location, Location
The Suncoast Chapter serves Hillsborough County, reaching from Tampa Bay north to Lutz, south to Ruskin, and east to Plant City, site of the 32nd annual Florida Native Plant conference. With so many places to choose from, some may wonder, “why Plant City? Is it the name?" If you only know Plant City as a blur south of the Interstate, you are not alone. After whizzing by it countless times, I finally slowed down to see what Plant City had to offer; it was truly a worthwhile decision. Here are some of the reasons why...

The Collins Street mural captures the history and culture
of Plant City for the passerby. Dedicated 1/10/2010,
it commemorates the 125th anniversary of the city's
incorporation. Depicting 53 total figures, the mural
includes 25 historical people and iconic city landmarks.
It turns out that Plant City is one of the few “walkable” towns in Florida, complete with historic buildings and murals. Though close to the urban sprawl of Tampa, it has retained the small town feel and heritage that flows from its unique history and location.

Plant City sits on I-4 between Lakeland and Tampa, and has about 35,000 area residents. Although it certainly is on the road to well-known tourist attractions, it is equally near diverse natural areas like the Green Swamp, Hillsborough River basin and Tampa Bay, Alafia River, Circle B Bar Preserve and the Lake Wales Ridge. We hope that everyone plans to visit the town’s natural surroundings on field trips and side trips while you are in the area (for a rundown on the field trips, see this blog post). High and dry or wet and wading, there’s a preserve or park that’s perfect for you in easy driving distance.

Plant City's slogan, Embracing the Future while
Preserving the Past
, is reflected in its modern City Hall.

The Venue
Our conference will be held on the Plant City campus of the Hillsborough Community College just down the road from our hotels. I must say the John R. Trinkle Center was another fabulous surprise; it is the perfect space for our conference—light, airy, great parking, a oak-shaded courtyard for the plant vendors and all the high tech gadgetry we need to hold a great conference. I’ve been to quite a few FNPS conferences, and this is among the best settings we’ve had. We're extremely grateful to the University of Florida IFAS, Gulf Coast Research and Education Center-Plant City for sponsoring our use of this facility.

Although it has changed in 100 years, Plant City holds
on to much of the character so evident in its heyday
Shirley Denton, president of the hosting Suncoast Chapter says, “we’re enthusiastic about our venue – a really modern facility in an old Florida community. I’m really glad that we can bring to FNPS a strong local heritage, great nature, and wonderful talks.”

Plant City, the Old and the New
Like any small town, there are families and businesses who have been part of the community for generations. The town retains much of its early character, with historic commercial and residential districts.

The Plant City Courier celebrates Plant City as the
state's largest inland shipping point, highlighting its
role as the hub of agriculture.

Plant City was originally named Ichepucksassa (according to Wikipedia), then became a cotton town named Cord. Eventually farmers switched to strawberries, and when Cord became an agricultural transportation hub, the town thrived, and had another name change. Apparently, naturally occurring phosphate nodules in the soil of surrounding flatwoods alowed vegetables, ornamentals and strawberries to thrive in the Florida sand. Though touted as Winter Strawberry Capital of the World and an agricultural wonderland, the town was not named for plants; it was named to commemorate the railroad magnate Henry Plant, whose trains made it all possible.

The annual Strawberry Festival in March soon became a Florida tradition which continues to this day, with its county fair attractions and famous country stars. (Strawberry lovers: Although strawberry season ends in early April, you can get a strawberry milkshake at Parkesdale Farm Market on Hwy. 92 west of town year round.)

The Strawberry Festival has been a spring destination
in Florida for years, as well as a setting for forced family
fun! Image from the Florida Memory Collection, State of
Florida Archives, Division of Library and Information
Today, the train no longer stops in Plant City but you can see the original train station in the historic downtown area, along with the shopfaces and homes of yesteryear. A walk around town and a drive in the country will show you how old and new can combine to blend the best of both worlds.

Janet Bowers, Suncoast Chapter, nominates the downtown Corner Store restaurant as her favorite place in Plant City. The Corner Store has unique sandwiches, wraps and salads made from organic sources, combined with a very friendly atmosphere. (They will be bringing us our conference lunches, by the way!)

The Suncoast Chapter participated in the local
Gardenfest last year. Gardening is a popular hobby
among Plant City residents.
Out of town, Janet tells us, Plant City is now home to Eco-farms where the owners grow organic, sustainable crops and make cane syrup. Other local farmers have expanded into blueberries, and a blueberry winery offers tastings. Plant City clearly continues to transform its agricultural heritage.

The Lodging
Evelyn Madonia is the face of the Red Rose Inn. She used
to work for her family's tomato business, but in recent
years she has been responsible for bringing glamour
back to the land of the strawberry.
You can’t lose staying in either hotel. The Red Rose Inn, just a few minutes away from the Trinkle Center along the frontage road, is, well, shall we say, eclectic!  You can't tell this book from its cover... From I-4, it looks like an ordinary, if really large, motor lodge, but just wait. The owners have put their hearts into making the hotel a resource for their community, with a southern flavor, and their food is legendary in the Tampa Bay area. Feeling adventurous? Book your stay in either the Rhett Butler or Cross Creek suite! See a great 2010 article at For those who prefer something a bit more conventional, the Holiday Inn Express is under 1/3 mile north of the Trinkle Center, and just south of the road that leads to the Red Rose.

On behalf of the Suncoast and Hernando Chapters of FNPS, we look forward to welcoming you to our region in May, and sharing what we are trying to protect here in the Natural Heart of Florida. Get ready by visiting

Edited and formatted by Laurie Sheldon

Thursday, April 5, 2012

Florida’s Fabulous Fabaceae Family

By Becca Massip

Figure 1: The Pineland Butterfly Pea, Centrosema arenicola,
is an endangered species found in Duval County, Florida
Photo credit: Shirley Denton
This post is one of a series from professor Nisse Goldberg's Plant Taxonomy students at Jacksonville University. FNPS blogger Laurie Sheldon assisted the students with their initial drafts, providing suggestions for editing and content development.

The Fabaceae family is known as the Pea Family. It is the third largest family amongst flowering plants, containing over 16,000 species. There are 314 species in Florida alone, 168 of which are natives! This family is found in temperate and tropical environments all over the world however, most species prefer seasonally dry habitats. This family is very unique because it can directly fix atmospheric nitrogen with the help of root nodulating bacteria.

Leaves: simple, trifoliate, pinnate, or bipinnate
Fruit: legume
Flower: zygomorphic or actinomorphic

Figure 2: Peas are healthy for the human body.
Photo credit: Bill Ebbeson
The Fabaceae family includes three subfamilies: Mimosoideae, Caesalpinioideae, and Faboideae. Species within Faboideae are common throughout Florida and are easy to detect by their butterfly-like flower shape (Figure 1). The flower’s petals make it easy for pollinators like bees, wasps, flies, butterflies, birds, bats, and beetles to take nectar. The Fabaceae family is most famous for its fruit, which is a legume, or pod. When the pod is ripe, it opens along the edges to release the seeds.

The Fabaceae family has many important uses. The seeds contain large amounts of protein and oil, which are healthy for the human body (Figure 2). Some herbs are grown for their grain, while others are grown to be consumed by farm animals. There are also many species in this family that are used for decoration due to their bright colors and unique shapes!

Figure 4: Sickle Bush, Dichrostachys
, is found throughout Africa.
Photo credit: Atamari
Figure 3: Wattle, the floral emblem of Australia.
Photo credit: Melburnian

Fun Facts

The peanut is a legume that develops below the ground!

The biggest pods of the Central American legume, Entada gigas, can be up to 5 feet long!


Sunday, April 1, 2012

Love Is In the Air or What's All Over My Car?

A Story about Live Oaks, Pollen, and Understanding

By Laurie Sheldon

Writing in a layer of pollen on a vehicle.
     Aah, spring… the sun is shining, the birds are singing, the oaks are leafing out and my neighborhood is plastered in yellow. No, we don’t have a Post-it® fetish. It’s pollen, and it’s earlier and thicker than usual this year. Don’t go hating on the oak trees, though - it’s not really their fault. They are simply responding to the climbing temperature. The fresh air and changes in wind which push out at least some of the pollen come from the cold fronts we normally have in early spring. These beneficial fronts have been m.i.a. this year, which has left us roosting in an inert yellow cloud.
     On the bright side, however, is the effect that this abundance of pollen has had on my curiosity. It occurred to me that, while fairly knowledgeable about zoophyly (pollination by animals including birds, bats, and insects), I knew little about anemophyly (wind pollination) other than the fact that it seemed like the plant version of throwing a “Hail Mary” pass. Since I had to blog anyway, it was a great opportunity to further educate myself and share that information in this article. So here goes…

Plants are Sexy
     For starters, I have often found that I forget plants are sexual creatures. Perhaps it’s because they never whistle at me. Who knows. The bottom line is that plants are wired to try to reproduce, and, among angiosperms, their flowers are what enable them to do so.
Male and female flowers don't always live together

  Some flowers have both male and female reproductive organs (stamens and pistils), and some have only one or the other. These are referred to as bisexual and unisexual, respectively. To make matters even more complex, sometimes the male and female flowers of the same species are borne on entirely different plants. This setup is known as being dioecious, a Greek-derived term for two houses. When a single plant has both male and female unisexual flowers it is called monoecious (one house).
      Now that I’ve broken down the basic reproductive components of flowers and the various living arrangements that unisexual flowers have, let’s consider the advantages and disadvantages of each. Bisexual flowers are generally much showier than unisexual flowers, but their brightly-colored petals and/or fragrances take a good bit of energy to create. Why do they bother? That’s how they attract animal pollinators, who will, in turn, carry pollen directly from the stamen of one flower to the pistil of another - usually without even realizing it. The work these flowers do to get all dolled up is balanced out by the lack of effort they have to put into pollination. As an added bonus, because the pollen is flying non-stop from stamen to pistil, the plants don’t have to produce pollen in excess of what’s required for fertilization. Bees are much more reliable than airlines for getting baggage to the appropriate destination.
Axial female bud, left; mixed male bud
with elongating catkins, right
     Oak flowers, by contrast, are unisexual (they have separate male and female flowers). This is fairly common among anemophilous (wind-pollinated) species. Male oak flowers (which contain the pollen) are apetalous (have no petals) and terminal (located at the ends of branches), which makes good sense if you think about it. There’s no point in putting energy into making the sort of flashy outfit needed to coax critters into transporting their pollen, and petals would act like a wind baffle, which would be completely counter-productive. Being at the outermost edge of a branch gives them prime wind exposure. In addition, the terminal buds that contain the male flowers are mixed - they contain leaves as well. These leaves wait until the flowers are done blooming before they unfurl, since they would only get in the way of pollen movement. Female oak flowers are  located in the angle formed between stem and leaf. This positioning is referred to as axillary.

The barely visible leaf within
a mixed terminal bud

Inbreeding - Plants Know Better
     Most of us will recognize that it’s probably a bad idea to have offspring with blood relatives. Even if it was socially acceptable, those children would not have much going for them as far as genetic variation is concerned. Apparently our oaks are aware of that too! Although they have both male and female flowers on the same plant, the stigma of the female flower is not receptive when the male flowers shed their pollen (like a plant version of the rhythm method). They have no choice but to pollinate and be pollinated by other oaks. Now, if you’re thinking, “hey, wait a second - isn’t it incestuous when live oaks pollinate each other since they’re in the same family? They even have identical first and last names (Quercus virginiana)!” The answer is no. You and I aren’t “kissing cousins” simply because we are both Homo sapiens, right? (Just nod your head here) The same rules apply for oaks.

Doing The Deed
Male flowers, swollen with pollen
     Now let’s discuss how oak pollination works. Let me set the scene: It’s the end of winter, and chilly evening temperatures have given way to warm spring days. This temperature swing prompts the production of auxins - hormones that force our oaks to increase their water intake. The oaks suck up water like nobody’s business, which causes the female flower buds to enlarge and the terminal buds to swell and burst open. Out roll the male flowers, shoulder to shoulder on a dangling stalk that looks like a cat’s tail. Not surprisingly, this flower grouping is called a catkin. The catkin dances in the breeze, continuing to elongate, each of its flowers becoming more robust with pollen (which is dividing and multiplying through meiosis). The female flowers open up and extend their stigmas to catch pollen from a nearby tree. Shortly afterward, the male flowers open up, show off their swollen anthers, then - BOOM - the anthers explode from all of the water pressure. The catkins sway to-and-fro, with anthers liberating an unthinkable number of microscopic pollen grains like confetti on New Year’s. The first grain to fall into the cradle of a female flower will stake its claim by growing a tube to bore into the female ovary, through which it will release sperm. Soon the female flower will have a “bun in the oven” which will eventually become an acorn. Incidentally, the word acorn is a concatenation of “ac” the old English for “oak,” and “cern,” Greek for grain.
Fallen catkin with anthers extended
and emptied

The Lonesome Losers
     Most grains will not make a meaningful connection, poor things. The male flowers they once inhabited will dry up and fall from their lofty perches, and the leaves they hung in front of will get the green light to grow. April showers will wash away all that remains of the grains that hoped to start something wonderful but ended up splattered across lawn furniture, patio screens, and driveways.
     So instead of getting irritated the next time you find yellow dust on your just-washed car or brown bits of catkin on the living room carpet, just stop. Breathe deeply. Sneeze if you must. Then proceed as follows:
(1) Consider how lucky you are that your destiny isn't pinned to an afternoon breeze
(2) Know that the pollen had hoped for more in life than to do a faceplant on your Honda
(3) Reflect on your new understanding of its unfulfilled potential
and (4) Remember that none of our majestic oaks would exist without the efforts a pollen grain forty microns long.

Left: Oak pollen grains as seen with a scanning electron microscope.
Right: The "Angel Oak," possibly the largest Quercus virginiana in the United States

All photos and illustrations by Laurie Sheldon unless noted otherwise