Bulbs, herbivory, and snakebites

Joe Shaw jshaw@opuntiads.com
Tue, 28 Nov 2006 15:48:53 PST
Hi Gang,
    Take a bite out of a wild onion bulb or try chomping on a wild potato 
tuber and you'll know that geophytes can taste awful or actually be 
poisonous.  Likely, one reason underground plant parts can be toxic or vile 
is because they have evolved chemical defenses to ward off insects and 
hungry vertebrates.
    Although any part of a plant can produce chemicals that deter herbivory, 
the underground parts seem like special cases.  Underground storage organs 
are rich repositories of food, and such is a bonanza for animals.  Why 
bother eating a leaf when a tuber provides far more nourishment in the form 
of complex carbohydrates.

    Some plants actually give off chemicals that are not nasty-tasting or 
poisonous but which mimic alarm chemicals emitted by insects--the thinking 
is that insects sense the chemicals and move to apparently safer locations.

    Some plants give off chemicals that inhibit the growth of other species. 
Extracts from the bulbs of wild garlic (Allium ursinum) inhibit seed 
germination and seedling growth of various plant species.  Perhaps such 
inhibitory activity is useful in the ongoing competition for soil water, 
nutrients, and light.

    Though plants have various abilities that evolved independent of humans, 
we humans have learned out to exploit the copious chemical synthesizing 
ability of plants, including geophytes.  Extracts from Crinum jagus are 
purported to protect against snake venom.  A recent scientific paper 
describes how C. jagus extracts, when injected into mice, appear to protect 
the animals from snake venom.  In particular, protection from carpet viper 
venom (Echis ocellatus), a snake found in West Africa, was claimed.



Conroe, TX

Rain last night, 70s this week, frost on the weekend upcoming

LINK:  Saw-scaled viper (carpet viper) info


CITATION:  Ode and Asuzu. 2006. The anti-snake venom activities of 
methanolic extract of the bulb of Crinum jagus (Amaryllidaceae). Toxicon. 


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