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Undercover Science

Finding the Perfect Match

Julianne Beck —  February 6, 2013 — 1 Comment
PHOTO: Norm Wickett looks at moss.

Dr. Wickett looks for liverworts growing under the cover of other vegetation on a previous research trip to Costa Rica.

In the deep green landscape of Vancouver, British Columbia, Norm Wickett stood spellbound.  As an undergraduate biology major at the University of British Columbia, he was enchanted by the seemingly endless ribbons of moss wrapped around the region’s natural areas.

“My heart is in mosses,” he shared during our recent conversation in his office at the Chicago Botanic Garden. “My first love in biology is mosses.”

Many of us non-scientists might consider this common plant—often seen lurking in shadowed, damp areas, to be a turnoff. But to Wickett, Ph.D., now a conservation scientist at the Garden, it presents an irresistible puzzle. How did this plant, likely one of the first to have lived on land, evolve from relatively few species during the Jurassic period to the 15,000 species living today? How did it adapt to all of the environmental changes that occurred?

“I’m attracted to more primitive plants,” said Wickett. He enjoys observing early species in the Garden’s Dwarf Conifer Garden.

As the recipient of a new grant from the National Science Foundation, Dr. Wickett is working to put the pieces together. “This grant is going to allow me to get back into mosses and it’s a great opportunity,” he said.

Part of the National Science Foundation initiative called “Assembling the Tree of Life,” Wickett’s project is one of many branches of study the organization is funding to explore how all life is related.

His work, he believes, will answer important questions about the evolution of all plants from mosses to the conifers and flowering foliage that ensued. Also, it will allow him to identify the ways in which past environmental events, such as climate change, influenced the evolution of mosses, other plants, and animals. This type of knowledge will help researchers predict how plants could respond to future environmental changes.

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The spore-bearing capsules of a species of Dicranum moss drew Wickett’s attention while he climbed to a high elevation in Costa Rica.

Wickett’s research process begins in growth chambers in the Garden’s Daniel F. and Ada L. Rice Plant Conservation Science Center. There, he nurtures plants for study. He then takes samples of them to capture the many strands of RNA, or genes, in each species. An expert in plant genetics, he uses new computerized technology to compare the genes of many species of moss and look for patterns.

Why are genetic patterns important? They draw a mazelike course scientists can follow to answer vital questions. Wickett will trace them from species to species in order to see which mosses share RNA and are therefore related. He will also use this information to determine when new species, which share some genes with earlier moss species but also carry some slightly different genes, emerged and what the environmental conditions were at the time that allowed them to thrive.

Timing is everything. He explained that the arrival of new genes must happen at the same time as a complimentary environmental condition for a new species to endure. For example, a plant which developed the ability to hold more water would have been successful during a drought, while it may not have survived during a flood.

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Wickett noticed this patch of Sphagnum moss in Costa Rica at a high elevation.

The genetic change can only last, according to Wickett, if it occurs at a time when it gives the plant a benefit in its environment. “It’s a combination of genetic changes in the moss and changes in the climate and finding the change that is most successful,” said Wickett. “For all these things the first step is that there has to be a change in the genes.” Then, he said, “we can go back in time using computer modeling to see what caused the changes.”  These are the pieces Wickett plans to assemble into a bigger picture of evolution during the next three years of his research project.

It is too early to predict where his discoveries may take him, but for now, at least, it is clear that his heart is in the right place.

 

Look for liverworts, a relative of moss, growing in the Greenhouses on your next visit!

It’s hard to believe that the Green Roof Garden has been in place for three full growing seasons already. Our horticultural and research staff is pleased to see how the green roof is growing and evolving as plants settle in and move around by rhizomes and reseeding. Despite the challenging weather of 2011 and 2012, the vast majority of the 240 taxa currently on the green roof have thrived. While our goal is to minimize the care and resources put into maintaining the roof, we had to give the plants supplemental water once in July 2011 and twice in June 2012 during periods of extreme heat and drought. Not surprisingly, the greatest stress was on plants in the shallow 4-inch-deep plots. But the great news is that plants rebounded quickly once they received the additional water.  

green roof aerial

The Green Roof Garden contains a mixture of plants that are commonly grown on green roofs and other taxa that are uncommon or untested for this use. The plant evaluation component is a particularly exciting aspect of our green roof—fully half of the 16,000 square feet is dedicated to testing a broad variety of new plants for green roof culture. In a way, the sky’s the limit on what we can try. In fact, we initiated a new trial of prickly pear cactus (Opuntia spp.) in 2012 to see how these succulents from the western U.S. perform next to our local species, Opuntia humifusa.

There have been many success stories on the roof, but here are just a few native plants that I’ve found particularly strong performers in 2012:

Pycnanthemum virginianum 4

Common mountainmint (Pycnanthemum virginianum) is native to eastern North America and found in dry and moist prairies and calcareous fens in the Chicago region. Plants remained ornamental and healthy regardless of droughty conditions; it is growing in the semi-intensive 8-inch substrate depth. While stress caused lower leaves to drop, plants flowered well and maintained strongly upright habits at all times. Plants were 22 inches tall and 10 inches wide in 2012 and the small white flowers were in bloom from early July to late September. Bees, moths, wasps, and flies are frequent visitors on common mountainmint.

salvia azurea var grandiflora pitcher's sage 2012oct01_4162Salvia azurea, Solidago rigida, Andropogon gerardii

Although pitcher sage (Salvia azurea var. grandiflora) is an introduced plant in the Chicago region, it is native to dry prairies in Illinois. Pitcher sage features exceptional sky blue flowers from late summer to frost. A serendipitous planting of pitcher sage, stiff goldenrod (Solidago rigida), and big bluestem (Andropogon gerardii) made a spectacular show last year. We’re growing pitcher sage in extensive to semi-intensive plots so flowering stems ranged from 30 inches tall in the 4-inch plots to 56 inches tall in the 8-inch plots.

Sporobolus heterolepis 2

Prairie dropseed (Sporobolus heterolepis) and the cultivar ‘Tara’ are being grown in the extensive to semi-intensive plots. Variable plant sizes, from 14 to 40 inches tall and 26 to 40 inches wide, were observed in the different plots. Leaves remained green throughout the growing season, even in droughty conditions, and turned a beautiful orange in autumn. The pungently fragrant flowers opened in August and remained effective for many weeks. Prairie dropseed is native to mesic and hill prairies in Illinois. ‘Tara’ is generally shorter than the species by about a foot and has darker green leaves and a vase-shaped habit.

Viola sagittata 4

Arrowleaf violet (Viola sagittata) naturally occurs in sandy old fields and dry prairies in the Chicago region, and is known to occur in sterile abandoned clay fields where the topsoil has been eroded off. Given its adaptability to poor soil conditions, arrowleaf violet was recommended for testing by Jim Steffen, one of the Garden’s ecologists. Arrowleaf violet bloomed from early April to early May and then again later in the summer. It is a generous re-seeder and has begun to pop up around the Green Roof Garden. Plants are grown in extensive to semi-intensive plots, but greater vigor has been noted in 6 inches of growing media than in 4 inches.