EEB337H1 - Families of Vascular Plants

Vegetative morphology


Plant identification frequently makes use of features of the vegetative, or non-reproductive, parts of a plant, such as the stem, leaves, and (less commonly) roots. The overall habit of a plant is also commonly used, at least where it is diagnostic at the taxonomic level at which one is trying to make an identification. At the whole plant level, life form classes are an example of the importance of overall vegetative morphology. For these reasons it is usually very important that herbarium specimens and their accompanying notes (subsequently incorporated into the label) include information about vegetative morphology. This variation is also described in Judd et al. 2002 (pp. 55-63, 81-87). Variation in vegetative morphology often relates to how the plant makes its living, and this in turn will often be a function of the environmental factors encountered by the plant during its life cycle. This interplay of plant and environment that molds the vegetative morphology is, more or less, the plant's ecology.

 

Top right: Leaf arrangement. From left to right, the examples are Clintonia borealis, Streptopus roseus, Mentha arvensis, and Lilium philadelphicum. Middle right: Leaf attachment. Lower Right: Leaf shapes. Below left: Shoot morphology in a caulescent (stemmed) plant. Below right: Shoot morphology in a rhizomatous plant. Note that in both caulescent and rhizomatous plants inflorescences may develop from axillary buds or at the shoot tip.

Illustrations on this page by T. Winterhalt, from The ROM Field Guide to Wildflowers of Ontario, pp. 16-18. © Royal Ontario Museum 2004.

Follow these links for more information about the organization of shoots, their modifications, and the terminology used to describe stems and leaves.

Right: Leaf composition. Top left, simple leaves; all the rest are once or twice compound leaves.

Some families have vegetative features that can make them instantly recognizable to the experienced botanist, such as the interpetiolar stipules associated with the opposite leaves of the Rubiaceae (e.g. Cephalanthus, Galium, Mitchella), or the pattern of leaf venation seen in the Melastomataceae (this feature is less apparent in Rhexia, the sole Ontario representative of this family), or in the genus Cornus.


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Please send your comments to tim.dickinson@utoronto.ca; last updated 06-Sep-2010