Saghatelyan, Anna .
Big Bend Region Flora Analysis.
The flora of the Big Bend Region of SW Texas, situated on the boundary of two subkingdoms, the Madrean and Boreal, was studied from a biogeographical perspective. It was then compared with Frontal and Central Asian sample floras, and analyzed. There are 1587 native species in 592 genera of 125 families in the designated flora. These species, based on their contemporary distribution outlines, were classified into 19 geographic (floristic) elements. The genera, based on their general distribution, were classified into 19 geographic groups. The flora has a complex pattern of connections. However, autochthonous xerophytes evolved from the Madro-Tertiary geoflora stalk predominate in it. Laurasian (Arcto-Tertiary) flora derivatives play a lesser role. The strongest connections of the flora are with that of Mesoamerica-South America. The madrean species (66% of the flora) and among them the Chihuahuan endemics (26% of the flora) are most numerous. South-western and western North American genera, followed by tropic/subtropical genera are much better represented than the northern and eastern American temperate genera. East-west Northern Hemisphere connections across the Atlantic show several different patterns. Most frequent ones are the following two, each including earlier and later migrations: 1) northern Tertiary migrations of the Laurasian mesophyllous genera (Juglans) via one of the northern land bridges and Cenozoic migrations, mostly from Asia (Astragalus) or from Europe (Linum); 2) diversification of older Madro-Tethyan subtropical genera along the Tethys seaway (Arbutus) and recent long distant dispersal from the Mediterranean (Limonium.) The third type of east-west migrations was probably along the southern Tethys shore. It involved some termophyllous Southern Hemisphere taxa originated or preserved in the Horn of Africa region (Andrachne) as well as eastward migrations of subtropical American genera (Lycium.)
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1 - McMurry University, Biology, McM Station Box 368, Abilene, Texas, 79697, USA
Big Bend Region
Presentation Type: Oral Paper:Papers for Topics
Location: Cottonwood B/Snowbird Center
Date: Monday, July 27th, 2009
Time: 1:45 PM