Botany Basics - Continuing the GILF Method, plus The Evolution of Plants and Flowers

Notes from the 2nd class of the Botany Conservation Course 
by Course Volunteer Phyllis Daniels & Course Coordinator Mary Kiesau

Dana Visalli, local botanist, educator and creator of The Methow Naturalist quarterly journal, was the second speaker in the Methow Conservancy's 2014 Methow Conservation Course “Botany: The Basics & Beyond.”  This is the 10th annual course.

Dana started off the class with a “side-bar” discussion of where plants came from.  Dana based his talk on his article, “Flora of the Methow: The Plants of the Methow in Their Evolutionary Context."

Dana said… Some sense of the vastness of time is helpful in understanding how life changed so much through history. One way to get a feel for time is turn its passage into a story. For example, if our 4.8 billion year-old Earth were condensed into a year, each month would represent 400 million years, each day would represent 13 million years, and each minute would represent 9000 years.

The oldest known biological cells are 3.5 billion years old, so they would have appeared on April 8 in our one year time frame. The first photosynthetic organisms (which were bacteria) are 2.4 billion years old and appeared on July 1. The first plants appeared 400 million years ago, on December 1, while flowering plants at 140 million years old appeared on December 21. Homo sapiens, which are about 250,000 years old, would have appeared at about 11:30 PM on December 31st. The life of an individual person would be about half a second (out of 32 billion seconds in a year).

The fact that 4.4 billion years went by before plants were able to colonize land just 400 million years ago suggests that this was a difficult assignment.  Previously all of life’s functions were conducted in an aquatic environment, primarily in the ocean. In the case of plants, reproduction, acquiring nutrients and carbon dioxide for photosynthesis, retaining water inside tissues, and defenses against predators all had to find ways to adapt to living on land.

To begin with life had to invent photosynthesis, which we take for granted but is a near-miraculous process.  Next, life had to invent sexual reproduction, which seems to have appeared about one billion years ago.  All life prior to this reproduced asexually by simply splitting in half.  Many of the showiest structures of plants exist to ensure successful sexual reproduction, including of course flowers. The enhanced variability of sexual recombination of genes also allowed plants to adapt more quickly and effectively to the challenges of living on land.  This ‘survival of the fittest’ is known as natural selection.

The Plant Kingdom is divided up into ten different groups, known as ‘divisions’ or ‘phyla,’ according to their evolutionary history.  Of these ten global phyla six are present in the Methow today.

Dana walked us through these six phyla from the earliest to the newest with each succession looking for “a better way” to grow, reproduce and survive.  In order: Mosses, Club Mosses, Horsetails, Ferns, Conifers, and Flowering plants.  See Dana’s article for more details on each of these divisions.

Flowers appear rather suddenly in the fossil record about 140 million years ago, and by 100 million years ago they had become the dominant plants in terms of species diversity. What evolutionary advantage did they develop that made them so successful?  About 150 million years ago a relationship between plants and insects began to develop, in which insects went from plant to plant foraging for food, and in the process picked up pollen at one flower and delivered it to another on a different plant. Directed transport of pollen by insects and other animals is now the dominant form of plant pollination.

Showy and fragrant flowers have evolved to attract pollinators, all in service to sexual recombination of DNA. This development of a symbiotic relationship between plants and animals was a level of complexity in ecosystems and on earth that had not previously existed. The partnership was so successful that flowering plants in a sense took over much of the terrestrial portion of the earth from the more ancient plants.

There is about one thousand times as much plant biomass on land than animal biomass. That means that of the approximately 500 billion tons of biomass on land, 499.5 billion tons are plants and only one-half billion tons is comprised of animals. The plant kingdom dominates the terrestrial landscape to a surprising degree.

Dana then switched gears to reviewing and teaching the “General Impression of Leaf & Flower” presentation, though he took out the “leaf” part to make things simpler.  Dana also created a “key” based on the presentation to reminds us all that the ID Groups should be viewed as hierarchical (does a plant have parts in 3s?  No, then does it have parts in 4s?  No, then does it have parts in 5s?  Yes, okay then is it bilateral or radial?....)  We reviewed what we learned last week, then moved on to learn the basic characteristics of the families in “Bilateral Symmetry” Group and the “Numerous Small Flowers in Tight Bunches” Group

Orchids have bilateral symmetry

In bilateral symmetry, only one plane will divide the plant into roughly mirror image halves.  (In radial symmetry, any number of cross-cuts may be done anywhere on the circle to produce a mirror image half.)

The families we studied in the “Bilateral Symmetry” group were:

Mint Family – petals fused; stems square, leaves opposite, plant usually aromatic, ovary with 4 seeds.  Includes; basil, salvia, purple sage, self-heal

Figwort Family – petals fused; stems round, leaves opposite or alternate, plant not aromatic, ovary with many seeds. Includes: paintbrush, louseworts, veronica, penstemons      

Pea Family parts

Pea family- petals free or nearly so; the upper petal is the largest, not spurred, leaves compound

Violet family- petals free or nearly so; the lower petal the largest and spurred, leaves simple

Some Buttercup Family plants like larkspur can also be in the bilateral symmetry group. 

The families we studied in the “Numerous Small Flowers in Tight Bunches” group were:

Silky Phacelia

Waterleaf family – stamens are long and protruding; stems and leaves often covered with rough hairs.  Includes: waterleafs and phacelias

Valerian – 3 stamens; corolla 5-lobed with a small spur or lobe at the bottom. Includes: Sitka valerian

Buckwheat-  Generally many flowers, individually small & inconspicuous,

 that may be clustered into showy inflorescences.  Perianth of two whorls of 3 tepals each.  Tepals are sepals & petals that are undifferentiated.  31 species in the Methow.  This is a difficult family to characterize because of the variations. The 3 genera presented here have easily observable variations.

Eriogonum heracleoides

·        Eriogonum (desert-buckwheat) – leaves mostly basal, not divided or toothed; Upright, nearly leafless stem; tight umbel of flowers; small shrub-like

·        Polygonum (knotweed or smartweed) – swollen joints on stem (the “knots”); flowers very small often in dense clusters at leaf joint or on narrow upright stem.

·        Rumex (dock) – leaves fleshy or leathery, often with basal rosette but also with leaves directly on stem; long clusters of green or red flowers at top of stalk.

Lomatium dissectum (Chocolate Tips)

Parsley family - Tiny flowers on stems that radiate out from a single point like an umbrella and then at the end of each flower stem there is yet another “umbrella” of smaller stems - a true compound umbel; leaves sheath stem, usually compound, often fern-like or carrot-like.  23 species in the Methow.  Includes generas: Angelica (leaf has a ‘thumb’), Lovage, and Lomatiums (aka desert parsleys) of which we have 8 very cool species.

We then began looking at flowers under microscopes and with hand-lenses and saw many wild and wonderful things…