Poa matris-occidentalis matris-occidentalis

Soreng, Robert J. & Peterson, Paul M., 2012, Revision of Poa L. (Poaceae, Pooideae, Poeae, Poinae) in Mexico: new records, re-evaluation of P. ruprechtii, and two new species, P. palmeri and P. wendtii, PhytoKeys 15, pp. 1-104 : 34

11a. Poa matris-occidentalis matris-occidentalis Figs 10 A-C 11 C-L

Description.

Leaf sheaths smooth, glabrous; collars glabrous; ligules abaxially glabrous. Lemma keel and marginal veins glabrous, between veins muriculate. Lodicules 0.3-0.4 mm long, broadly lanceolate, with a lateral lobe.

Distribution.

This subspecies is known only from Cerro Gordo, Durango.

Ecology.

Known only from a single locality at Cerro Gordo, between 3130-3200 m where the species was found growing on steep, rocky, and grassy slopes beneath open forests of Pseudotsuga menziesii (Mirb.) Franco, Quercus spp., Pinus spp., with other associates, such as: Arctostaphylos pungens Kunth, Bromus carinatus Hook. & Arn., Bromus richardsonii Link, Muhlenbergia cenchroides (Humb. & Bonpl. ex Willd.) P.M. Peterson, Trisetum viride (Kunth) Kunth, Festuca sp., Carex sp., and Agrostis sp. Flowering September and October.

Specimens examined.

Mexico. Durango: Transect from Paseo de Cerro Gordo to the top (cumbre), 23°12'31.1"N, 104°56'53.0"W, 3136-3348 m, 9 Sep 2006, P.M.Peterson 20011 & F. Sánchez-Alvarado (CIIDIR, US).

Discussion.

Cerro Gordo is quite remote from other high peaks in the area as it takes nearly 10 hours of driving from Durango along a dirt road to reach the base of the mountain, just south of Maiz Gordo. There are other mountains in Durango that approach this height and it would seem reasonable to assume that this species might occur on these.

Figures

Figure 10. Poa matris-occidentalis P. M. Peterson & Soreng. A-C Poa matris-occidentalis subsp. matris-occidentalis A habit B inflorescence C sheath, ligule, and blade D subsp. mohinorensis Soreng & P. M. Peterson D sheath, ligule, and blade. Drawings from Peterson et al. (2006), A-C drawn from holotype collection (Peterson 19145 & Sanchez-Alvarado) D drawn from holotype collection (Nesom 6475 & McDonald).

Figure 11. Poa matris-occidentalis P. M. Peterson & Soreng. A, B Poa matris-occidentalis subsp. mohinorensis Soreng & P. M. Peterson A spikelet B floret; C-L subsp. matris-occidentalis C spikelet D floret E lower glume F upper glume G floret H palea dorsal view I palea ventral view J perfect flower, stamens, ovary, and lodicules, all enclosed in palea K lodicules L young caryopsis. Drawings from Peterson et al. (2006), A, B drawn from holotype collection (Nesom 6475 & McDonald) C-L drawn from holotype collection (Peterson 19145 & Sanchez-Alvarado).