Plants are Cool Too! (All Episodes)

The “Plants are Cool Too!” series is supported by the Botanical Society of America (BSA) and hosted by Dr. Chris Martine. Here you will find all episodes of the series in reverse chronological order (last-in-first-out).

Ecologists have hypothesized that there has to be a level of disturbance acting pretty regularly on communities. The intensity of disturbance has to be “mild” so that it doesn’t wipe every living thing but clear out some habitable zones for re-colonization by some species that have less competitive properties. The Intermediate Disturbance Hypothesis explores just that. It predicts that in the absence of disturbance highly competitive species will eventually exclude others and in the end the ecosystems will be dominated by very few “bully” species. This latter prediction is known as the Competitive Exclusion Hypothesis. Legumes (Fabaceae) are quite interesting plants that have established a fascinating alliance with nitrogen-fixing rhizobium bacteria in their roots. Thanks to their symbiotic ability they are successful colonizers of nitrogen-poor soils and can be highly competitive in hot and dry habitats. However, they can be competitively excluded. Here in this episode, we meet the legume Blue false indigo (Baptisia australis) growing on river scour prairies. Scours can be extensive especially when the rivers freezes powerful enough to clear woody vegetation. Global warming is reducing freezing events and river scours are diminishing.

In this next episode, we go to cliff faces of Pennsylvania in search of a rare plant species, the golden corydalis (Corydalis aurea) restricted to these habitats. What makes a plant rare has multiple explanations and botanists are always keen to find the answer. Plant-animal interactions have been extremely effective in shaping life around us. Seed dispersal is one of the prerequisites of plant life cycle and could become a factor in rarety. Animal-mediated seed dispersal can take many diverse forms. Plants may use seemingly unusual adaptive tricks for transport of propagules. For instance the African plant Ceratocaryum argenteum (Restionaceae) emit a mixture of volatile chemicals present in herbivore dung. For obvious reasons, dung beetles become attracted to these seeds strikingly resembling to the droppings of antelopes.

In some extreme cases seed dispersal may depend on rather rare occurrences and could be linked to rarity of certain plants. Rattlesnakes have been shown to aid dispersal and germination of grass seeds by preying on rodents with specialized cheek pouches for carrying seeds to their nests. Such rare secondary seed dispersal events could be key survival strategy to some plants. Similarly in an island of the Canarian archipelago researchers have demonstrated that the seeds of a seeds of a wild tomato (Lycium intricatum) were dispersed by shrikes (Lanius excubitor) preying on lizards (Gallotia atlantica). Lycium seeds were correlated with the presence of lizard remains in shrike pellets and seeds from shrike pellets showed higher germination rates compared to those from uneaten fruits and lizard droppings. Cliff faces such as those of Pennsylvania are significant copperhead snake habitat. Who knows perhaps a similar biological interaction maybe at play affecting in the rare golden corydalis.

Mountains of Philadelphia have been strip mined for coal relentlessly for more than 200 years. Surface mines created vast areas of degraded lands. Coal has been a massive contributor to the accumulation of carbon dioxide in the atmosphere leading to mercury pollution with subsequent biomagnification throughout the food chain, ocean acidification and global warming.

Never underestimate urban habitats. Even in New York City you may encounter an exciting island of wildlife in a sea of concrete asphalt and steel. A little known fact: Manhattan itself is 1/8th wildlife area. Urban forests are scientifically neglected habitats but are getting more attention. For instance, check out the Earthwatch project in Boston for instance, where volunteers regularly census the urban trees as a part of a citizen science project lead by Dr. Vanessa Boukili.

Continuing with the urban ecology theme, in episode 7 Dr. Martine joins urban botanist Marielle Anzelone to visit Inwood Hill Park of Manhattan. Marielle Anzone is an ambitious figure who came up with the freakish sounding idea of “pop up forests” in downtown NYC. During their walk they introduce us to Chestnut Oak (Quercus montana) a distinct ridgetop tree which can survive shallow soils with rockbed underneath, American witchhazel (Hamamelis virginiana) which was widely used by native Americans with anti-inflammatory properties, lowbush blueberry (Vaccinium spp.) and tuliptree (Liriodendron tulipifera). Tuliptree is generally the tallest of the eastern hardwoods with a very rapid growth rate. ”The Queens Giant” which measures 133.8 feet (40.8 m) in height is the tallest tree in NY and could be a little over 200 years old. According to the Native Trees Society the tallest tree in Eastern North America is a Yellow Buckeye (Aesculus flava) measured in West Virginia. Although impressive sounding these trees are not old-growth as foresters, wildlife managers and ecologist generally call but second-growth. A second-growth forest is a young forest that grows in place of the old-growth forest. Today almost entire Eastern North America is one massive second-growth forest cleared by the European settlers. Inwood Hill Park of Manhattan is one of them.

What would it be like to live in an asphalt crack? Some plants can inhabit most extreme habitats like the lava flows and thrive. In this new episode of the two part series the filming crew visits Dr. Lena Struwe of the Rutgers University, who studies “super-evolutionary” weeds adapting to live on human-dominated urban habitats. Throughout the documentary we are introduced with the term extremophile and we also get to meet with one particular plant species demonstrating a strong evolutionary adaptation to live on asphalt crack: The carpetweed (Mollugo verticillata).

What is a weed? A plant whose virtues have never been discovered.
–Ralph Waldo Emerson

Next, the following mini episode takes us to Ka’ena Point in Oahu, Hawai’i. Marian Chau and Kimberly Shay introduce us to a conservation project on endangered/threatened coastal species in Hawaii. In 2011, a 2133 foot long predator proof fence was constructed at Ka’ena Point. The fence encompasses 60 acres of land and since it’s completion has had a clear impact on the rise of the total population of ground nesting seabirds and plants including Wedge-tailed Shearwater, Laysan Albatross, Ohia, Sandalwood trees, and many other species.

Hawai’i islands are the most isolated group of islands on Earth and thus are very special among biologists who study speciation and endemism. It’s flora is very rich. Among 1894 species of flowering plants 850 are endemic. Hawai’i archipelago is home to the largest co-evolved adaptive radiation on any island archipelago. Adaptive radiation of 23 species of Hawaiian honeycreepers (more than 16 species became extinct since Human arrival) and lobelioids with 126 species described have co-evolved over few millions of years. Unfortunately, many endemic species have gone extinct or are near-extinction mostly because of non-native species introduced by Humans to the islands.

In the fifth episode, we tag along an international expedition carried out into Chihuahuan Desert. Dr. Mike Moore of Oberlin College introduces us to a few interesting plant species including a new species of Ring Stem (Anulocaulis spp.) belonging to the Nyctaginaceae (Four O’Clock) family and an unidentified new mustard species that grow on tough gypsum soil. The plant family Nyctaginaceae is called “four-o’clock” because species belonging to this family have their flowers open in late afternoon and close by morning which is a typical desert plant adaptation.

Plants living on gypsum soil are interesting because under drought conditions their roots have the capacity to extract water bound to mineral. An isotopic analysis of sap water of one such plant (Helianthemum squamatum) in Spain has shown that close to 90% of the plants water was taken from gypsum. Gypsum is a rock-forming mineral also found in Mars.

Formation of new species has always been a core question for biologists. When organisms mate with others spread over a large area this enables a stable species. Gene flow helps preserve species identity. Natural selection is one of the ways to evolve into new species but not the only means. Isolation were seen as a prerequisite for speciation. Evolution in isolation is a quite distinct way to produce new species. How do new species form in the absence of no genetic barrier for gene flow? Biologists call this type of evolution sympatric speciation. As the scientists in this episode state, specimens collected from the field that physically look identical can be quite different when their genetic material is examined.

The fourth episode of the series documents hawk moths in particular white-lined sphinx moth (Hyles lineata) which fly for miles in the deserts of southwestern United States each night in search of flower nectar. These moths form a very crucial part of plant-animal interaction that ensures pollination of two groups of desert wildflowers belonging to the family Onagraceae including sundrops and evening primroses (Oenothera). Dr. Chris Martine joins Dr. Krissa Skogen of Chicago Botanic Garden. Together they help us witness night time pollination in New Mexico’s White Sands National Monument:

You can read more on “behind the scenes” notes of the episode four from the blog of blog of Dr. Krissa Skogen. As always nature is extremely finicky. As in the hawkmoth filming case sometimes you wait and wait and wait and just as everybody begin to think nothing is happening the long awaited event will happen…

The third episode of the series focuses on Eastern skunk cabbage. It was filmed in the Adirondack Mountain region with guest Dr. Rachel Schultz, assistant professor of wetland ecology at SUNY Plattsburgh:

The second episode of the series was filmed in Idaho in August 2012. It covers exquisitely preserved fossil remains of a long-vanished forest from 20 million years ago. This time period is a distinct stretch in evolutionary timeline known as Miocene epoch when the global climate started to cool down and boreal forest started to take over in northern lattitudes:

In the first episode of the series Dr. Martine and Dr. Maggie Koopman explore the habitat, life cycle, morphology and ecosystem of Sarracenia alata, a species of carnivorous pitcher plant known as “The Pale Pitcher Plant”.

Pitcher plants can be an effective biological remedy against invasive insects. Bee-killing Asian hornets (Vespa velutina nigrithorax) are spreading across Western Europe. Curiously in a botanical garden in Nantes, France a Sarracenia pitcher plant native to Massachusetts was found to be efficiently trapping the invasive wasps attracted to the plants nectar. European hornets on the other hand never fall victim to these plants.

Biologists have shown that a tropical pitcher plant has a remarkable adaptation for varying the slipperiness of the rim of its trap (the peristome). In Borneo, the pitcher plant (Nepenthes rafflesiana) traps sporadically large group of ants from the same species. In experiments where the trapping surfaces were kept continuously wet the plants no longer captured large groups of ants. When scout ants find a pitcher trap full of sweet nectar, they return to the colony and recruit many more ant workers. A super-slippery trap will capture most of these scout ants preventing recruitment of more ants. Now the story gets better: It seemed as if something plays with the stickiness dial on the pitcher plants traps. For part of the day the peristome stays dry and sugary to ensure that scout ants discover the candyland and get super excited to return to the colony. later on, the trap becomes wet and slippery and large numbers of recruited ants get captured.

Pitcher plants most certainly have a rich body of natural history.

Plants unfortunately get less attention from wildlife filmmakers. This is most probably due to a narration problem. When we see animals in a film we more or less can interpret what we are seeing. Natural history of plants require some additional story telling simply because their life cycles and interactions with other living and non-living things around them are not very obvious.