EEB337H1 - Families of Vascular Plants


Plant families may be characteristic of particular habitats or manners of making a living, so that knowing where or how the plant grows may help to identify it. For example, several families in Ontario comprise exclusively aquatic plants, such as Alismataceae, Azollaceae, Butomaceae, Cabombaceae, Callitrichaceae, Haloragaceae, Hippuridaceae, Hydrocharitaceae, Isoetaceae (mostly), Lemnaceae, Limnanthaceae, Marsileaceae, Najadaceae, Nelumbonaceae, Nymphaeaceae, Podostemaceae, Pontederiaceae, Potamogetonaceae, Ruppiaceae, Salviniaceae, Zannicheliaceae, and Zosteraceae. Others may comprise exclusively achlorophyllous parasitic or saprophytic plants, such as Cuscutaceae, Loranthaceae, Monotropaceae, Orobanchaceae, Santalaceae, and Viscaceae. Ecology may be useful in this way at other taxonomic levels as well.

Note, however, that of all the sources of taxonomic data mentioned, ecology is likely to be least useful since most families have diversified considerably and have members that make their living in a variety of different ways. Only some families are restricted to a single way of making a living (see the lists above). Categories like trees, shrubs, herbs, or climbers ("vines") typically represent a great variety of families of which only a small number are resticted to just one of these life forms. In general it is the vegetative morphology of a plant that relates to how it makes a living.

How a plant makes it living will be intimately linked to the environment in which it is growing. For this reason vegetation ecologists may find it important not only to assemble a list of all the plant species encountered in a particular habitat, but also to categorize these species according the their vegetative morphology into life form classes. In this way, the habitat is described in terms of the frequency distribution of the different life forms (life form spectrum). Life form classes were first described by the Danish botanist C. C. Raunkiær (1860 - 1938).

Instead, ecological specialization may be much more apparent at the level of genus or species.

| What are plant families? | How do we distinguish them? | How and why do we study them? | Selected vascular plant families of Ontario | Reading List | Course outline |

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