Thorny Questions

Amanda Neill neilla at MAIL.BIO.TAMU.EDU
Mon May 15 15:30:06 CDT 2000


>Richard L. Brown wrote:
>Why is the tree concentrated in the Blackbelt and not common in >bottomlands
>and other areas that have rich soils to support this tree?

     In east-central Texas, I have found that both Sideroxylon (Bumelia) and Maclura are often found in rich moist bottomland soils.  The extremely thorny Gleditsia (huge branching thorns on the trunks) also frequents the bottomlands;  I know of no thornier species of woody plant locally!  However, Robinia, Zanthoxylum, Parkinsonia, and Prosopsis all are found in higher, drier areas.  When I think about where these plants prefer to grow in our area (~38 in. of precip. annually, mixed grassland, savanna, and forest), I find it does give clues about their distributions.  As we are at an ecotone between humid forests like that found in the eastern US, and the arid grasslands and scrub found in western Texas, the plants at their eastern limits grow high and dry, while the plants nearing their western limits prefer to grow low and wet.
   Therefore, the Maclura at its most eastern distribution (Mississippi) grows in savannas.  I think almost everywhere SOME plants have produced thorns as an efficient method of protection against herbivory.
Amanda


~~~~~~~~~~~~~~~~~~~~~~~~~~
Amanda  Neill
>>>>>>>>>neilla at mail.bio.tamu.edu
Department of Biology
Texas A&M University
3258 TAMU
College Station, TX 77843-3258

wk# 979-845-3397 (voice mail)
hm# 979-260-9933
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