The purpose of this guide is to build a bridge over troubled waters. The uneasy water refers to the current split in botany between academic botanists, who specialize in systematic botany, and field botanists, often not employed by a university, who specialize in recognizing species with little benefit of systematics. Systematic botanists know a great deal of evolutionary theory but often have a difficult time identifying species out in the field, whereas field botanists specialize in identifying species in the field, but often do so with little knowledge or reference to evolutionary theory. The systematic botanists tend to look down on the field botanists, which they see largely as diletantes without much "real" botanical knowledge. The field botanists, while realizing they do not share the same level of prestige as the systematic botanists, tend to regard the academics as absent-minded professors who never stop to smell the roses, and who are of little use out in the field.
One of the reasons for the gulf is that there has been no field guide for field botanists that use a systematic approach to botany. Most flower guides are based on a strict hierarchy of selections. The field guides are based on random criteria that bear little or no association with evolutionary relationships: Peterson is based on color of flower; Audubon on the color of flower, and Newcomb on thenumber of petals. Often flowers on a page come from widely different families, seen in evolutionary terms, and thus have no direct connections. (An excellent guide book is the old Britton and Brown series, Gleason, 1952, but the guide need serious updating, especially for the scientific names of the species, and its three volumes makes it very bulky to use.)
The book that should be used in the new picture book that goes with the Gleason and Cronquist guide book. The two books are meant to go together.
It is usually the rule that beginners make the wrong choices when trying to identify a given flower. This is alright because the reader is getting used to the book. The user, however, is not learning anything about evolutionary relationships. Milling around in an evolutionary/taxonomic book is much more productive, than milling around in a more random book based on flower color or number of petals.
This guide is based more on a gestalt rather than relying on a hierarchical approach that uses one characteristic of a plant at a time in order to identify it. The human brain is much more sophisticated than this hierarchical approach. Those people who become expert in plant identification certainly do not use any rigid hierarchical system. Those very good at plant idlentification use many criteria to determine the identity of a plant.
In this book, identification system is based on the subclass system of taxonomy. There are six subclasses in the dicot group and four in the monocot group. The identification of the proper subclass can be made on the basis of a gestaltic evaluation of the overall flower and plant or the identification of the family (with subsequent treatment of the family within the subclass). Identification by subclass is based on a number of factors instead of being restricted to just one. For instance, to identify a water-lily flower, one notices the fact that many magnolia subclass flowers are bowl-shaped with little distinction between sepals and petals, and that there are many stamens, and separate carpels. Therefore, the identification of the flower is not only by the so-called floral formula (consisting of the number of petals, sepals, stamens, and carpels and whether these are fused or not), but also on other considerations such as the leaf patterns.
Among the benefits of using the evolutionary/taxonomic guide are that such a guide uses evolutionary principles and thus teaches the user evolutionary principles and relationships; the flowers on a page are related to each other; and replacing the keys with tables, that are similar to cross-tabulations, which makes it easier to make generalizations about the common characteristics of a related group of flowers. (After all, cross-tabulations are part of the method of statistical reasoning, while keys are not.)
Most people I have talked to who are not academically trained botanists, and even some who are, say they really do not like keys or that they never use them at all, relying on pictures instead. The field guides themselves do not use keys. Rather they use tables to get the user to the appropriate section of the guide.
Keys are terribly confusing because they keep changing the variables (or attributes) used to describe the plants. This leaves the user confused. It is virtually impossible to get a quick overview or gestalt from glancing at a key. In contrast a table keeps its variables constant and every cell unit is described within the categories of these variables. The same numer of total factors can be used in a table as a key, but the difference is that the more unique factors are delineated closer to the cellular level than at the main variable level. With a table, the user can get a quick overview of the plants in question because of the costant variables or factors and because there is a built in correlation in most tables. The values of the variables in the rows or columns gradually increase over some dimension(s), such as degree of evolutionary advancement, size, complexity, etc. This built-in correlation aids in quickly getting an overall view because the correlation can often be seen in the table itself. The table becomes somewhat of a graph in the sense that the table shows the relationships that graphs shows, such as where the values of one variable increases (or decreases) the values of the other also increases (or decreases).
THE EVOLUTION OF FLOWERS
The earth originated some 4.5 billion years ago. It took around a billion years before life originated on earth, at 3.5 b.y.a. Only about 560 million years ago, algae developed. It took more than 100 million years more (430 m.y.a.) to develop primitive members of the plant kingdom known as bryophytes (i.e., liverworts, hornworts, and mosses). From the divion of psilophytes (whisk ferns), a genus known as Cooksonia developed about 410 m.y.a. From this genus developed Rhyniophytina (400 m.y.a.), which in turn gave rise to ancestors of the gymnosperms (naked seed plants) and the seed ferns around 310 m.y.a.. (Dates from Thomas 1981.)
Cronquist (1988) calculates that the dicot flowering plants evolved from the pteridosperms (seed ferns) around 112 m.y.a. (The monocots arose around 100 m.y.a.) From the seed ferns developed the Cycadicae (cycads) with its five orders. From the order known as Caytoniales came the flowering plants themselves. The angiosperms may have developed on the Australian plate when it was part of Gondwanaland. The earliest angiospern was probably an evergreen woody plant with alternate, simple, entire, exstipulate leaves with pinnate net venation. The flowers only had leaf-like tepals, where there is no clear distinction between sepals and petals, or no petals at all, onlys sepals. The numerous stamens were in a spiral arrangement.
The main way in which botanists determine whether a plant is primitive or advanced is to examine the female reproductive structures. One of the features they particulary pay attention to is the placentation type within the ovary. In the field, however, one cannot examine the placentation type. So the field botanist has to rely on other characteristics that are not as highly correlated to the subclasses, orders, and genera. Some of the features the field botanist uses ine plant identification are listed below along with the characteristics that considered primitive or advanced. Some of these characteristics are only weakly correlated with evolutionary order. That is why they the characteristics have to be used in a gestaltic approach to evaluate the overall look of the plant, and especially of the flowers.
|leaves||alternate||opposite (but within the Aster family, opp lvs are primtiave & alt lvs are advanced)|
|leaf blade||simple, entire, pinnately net-veined||divided, toothed or lobed, non pinnately net-veined|
|buds||plain||with stipules (designed to protect the bud)|
|flower type||bowl-shaped||fused parts (Aster subclass esp.); sepals look like petals (Iris family)|
|reproductive system||perfect||unisexual (prevents self-pollination); weak correlation|
I. Group One -- Little Fusion of Parts
Here are the most primitive plants. The flowers are often bowl-shaped. They have numerous and often showy stamens, open flowers (bettle-pollinated), and little distinction between petals and sepals (often called tepals). There are at least three groups here. The open, bowl-shaped flowers, flowers where the tepals fall off leaving only showy stamens and those with no petals, but with fused sepals.
2. WITCH HAZEL
These are largely wind-pollinated species. Many are tree with catkins, with just a few herbs. Only one family among wildflowers is located in our area and these nettles have inconspicuous flowers in the axils of the flowers.
3. PINK (indistinguishable).
Many of the pinks are succulent halophytes. There are two large groups, those with no petals and those with petals in tubular shapes with a flat platform (petals often white or pink and notched). There are at least three groups here: those with no petals, no sepals; sepals only (no petals); and separate petals, but fused calyx.
II. Group Two -- Growing Fusion and/or Distinct Petals
4. DILL is largely a remainder category. There is partial fusion (either petals or speals, but usually not both. There are three kinds: hibiscus-like (mallows); insectivorous/parasitic (pitcher plants, sundews, Indian pipe); and paired stamen (mustards).
This subclass contains plant species with very distincat and separate petals with well-developed nectary discs. There are at least three kinds: petals only, no sepals (# 0); separate petals, regular; and those with separate petals, but ones contained in irregular-shaped flowers.
6. ASTER SUBCLASS
Aster subclass flowerws have fused petals and often both the petals and sepals have fusion. Not considering the Aster family
(Asteraceae), there are at least two kinds: those with fused petals, regular-shaped and those with fused petals, but which are irregular-shaped. The aster family is characterized by a congregation of flowers.
I. FLOWERING RUSH
Here there are many aquatic plants. The stamens are double the number of petals. There are at least two kinds: one with petals falling early and the other with petals that look like petals.
This class is characterized by species that have a spathe (hood) and spadix (spike). The stamens are six in number.
Here the petals and sepals are distinct with six or three stamens, along with unisexual species with no petals or the petals are like sepals, many of them semi-aquatic. (The latter group includes rushes, sedges, and grasses, but these are only mentioned in this book because of the great number of species.)
Most of these flowers have sepals that look like petals, with vaired number of stlamens, 6, 3, or 1-2. Here are the lillies, irieses, and orchids. There is one small group where the sepals are not petal like, which includes Smilax (greenbrier).