thorny questions

Dra. Heike Vibrans L. heike at COLPOS.COLPOS.MX
Tue May 16 20:44:43 CDT 2000


Dear taxacomers,

here in Mexico vegetation tends to become thornier (and more allergenic
and various other disagreeable things) when the climate becomes drier;
that is, you find thorny forests at the ecotone with shrubby vegetation
types, and thorny shrubs at the ecotone with grasslands. The popular
explanation is that if you can't grow fast for lack of resources,
you have to protect what you do grow.

Also, there are some grasses that use thorn-type structures for
defense (Cenchrus for example, a curse of fieldwork). I have heard
somewhere that awns are also considered a defense mechanism.

By the way: in German "Stachel" corresponds to prickle in English, and
thorn and and spine to "Dorn", which can be differentiated in
"Blattdorn" if it derives from a leaf, "Sprossdorn" (modified branch)
or "Nebenblattdorn" (modified stipules).

Greetings,

Heike

-------------------------------------------------
Dra. Heike Vibrans L.
Laboratorio de Etnobotanica
Especialidad de Botanica
Colegio de Postgraduados en Ciencias Agricolas
km 35.5 carr. Mexico-Texcoco
56230 Montecillo
Mexico

e-mail: heike at colpos.colpos.mx
Tel.: + (595) 20200 Extension 1335, secretaria 1331
      comutador desde el D.F. 58 04 59 00
Fax. y direccion directa: + (595) 20247
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