Systematics Section / ASPT
Strahan, Robert , Allred, Kelly W. .
A Morphologic Evaluation of the Aristida gibbosa Complex (Poaceae: Aristideae), Including A. marginalis, A. orizabensis, and A. sorzogonensis.
The genus Aristida L. comprises some 250-350 species, characterized by a panicle inflorescence, one-flowered spikelets with relatively large glumes, often larger than the floret, florets with three awns, the two lateral awns absent or much reduced in some species, and a sharp pointed callus with a tuft of hair at the base. The genus has its share of taxonomically difficult species complexes. Members of such groups often differ only slightly morphologically and commonly overlap in their geographic distribution. The Aristida gibbosa complex is one such group. The New World Aristida gibbosa complex is characterized by the following two features: 1) floret sulcate, and the margins of the lemma involute ; 2) callus short, 0.3 – 0.4 mm long, the attachment scar circular and tiny, 0.2 – 0.3 mm in diameter. Taxonomic relationships among Aristida gibbosa (Nees) Kunth, Aristida marginalis Ekman, Aristida orizabensis Founier, and Aristida sorzogonesis J.S. Presl based on morphological variation were assessed by principal component analysis (PCA). Recent treatments have subsumed the names A. marginalis, A. orizabensis , and A. sorzogonesis under the name A. gibbosa . Results of the PCA indicate two distinct clusters corresponding to A. gibbosa and A. sorzogonesis. The two taxa are distinguished by a number of vegetative and spikelet features. Aristida sorzogonesis includes pulvinate and epulvinate growth forms.
Log in to add this item to your schedule
1 - New Mexico State University, Department of Animal and Range Sciences, Las Cruces, NM, 88003, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM