ILLUSTRATED FLORA OF EAST TEXAS - Brit - Botanical Research ...

GUIDE TO TOXIC, POISONOUS PLANTS/INTRODUCTION 19
Many plants listed as endemic to Texas in Correll and Johnston (1970) have since been
found in immediately adjacent areas. Therefore, for current information on endemics we are
following Carr (2002b, 2002c) of the Nature Conservancy of Texas, who generously contributed
his data on Texas endemics. This information is given in the descriptions following
a plant’s Texas distribution and is also summarized in Appendix 11. In order to make Texas
endemics easily recognizable in the text, the symbol E is placed at the end of such species’
taxonomic treatments. Relatively few plants are endemic to East Texas; these are indicated
by the symbol T in front of the scientific name.
For plants whose place of origin is outside the continental United States, the symbol
I is placed at the end of the species’ taxonomic treatment. A symbol to allow such introduced
species to be recognizable at a glance seemed a useful inclusion (Schmid 1997).
However, the question of defining “introduced” proved more difficult. For example, all
species native to the U.S. somewhere outside of East Texas could have been considered
introduced; similarly, introduced species could have been defined as all species not native
to the state of Texas. Ultimately, we decided to use symbolic representation only for species
not native to the United States. However, all species not native to East Texas have their area
of origin indicated in the descriptions.
INFORMATION ON TOXIC/POISONOUS PLANTS
Notes on toxic/poisonous properties (indicated by the symbol ) are given in the synopses
and at the end of the treatments of various taxa. This information has been obtained from
a variety of cited sources, particularly the authoritative Toxic Plants of North America by
Burrows and Tyrl (2001). Note, however, that a lack of information about toxicity does not
indicate that a plant is safe, and no plant material should be eaten unless one is sure of its
edibility. Indeed, most plants have not been tested for toxicity and all should be considered
potentially dangerous unless known otherwise. Though technically a poison is a substance
that has properties harmful or fatal to an organism, and a toxin (a more specific term) is
any of various poisonous substances that are specific products of the metabolic activities of
living organisms (Gove 1993), the terms have been used synonymously in the text. Most
toxins are probably defensive compounds that evolved to protect the plant from herbivore,
bacterial, or fungal attack. While there are no general rules on precisely predicting plant
toxicity, there are rules of thumb among botanists about certain plants that are more likely
to be toxic—e.g., avoid eating unknowns in the carrot family (Apiaceae, which contains
some of the most toxic species known), the potato family (Solanaceae, also referred to as
the deadly nightshade family and the source of numerous toxic alkaloids), the buttercup
family (Ranunculaceae, with many species containing alkaloids or other toxins such as
glycosides or saponins), the aroid family (Araceae, with raphides—bundles of microscopic,
needle-like calcium oxalate crystals—and various toxins), the death-camas family
(Melanthiaceae, with highly toxic Veratrum alkaloids), and anything with milky or colored
latex or sap (e.g., members of the Asclepiadaceae—milkweed family, the Apocynaceae—
dogbane family, or the genus Euphorbia, the spurges).
In case of poisoning by plant material or any other source, the TEXAS POISON CENTER
NETWORK can be reached at 1-800-222-1222. This number connects you with the nearest
poison control center anywhere in the U.S., 24 hours a day, seven days a week. Poison control
centers can also be reached indirectly via the emergency number 9-1-1. Information can
also be found at the web sites of the American Association of Poison Control Centers at
http://www.1-800-222-1222.info/ or http://www.aapcc.org/.