Phological connections. Key to the subspecies of Poa matris-occidentalis 1 Sheaths of lower leaves smooth, glabrous; collars order Dalfopristin smooth or with a few hooks, glabrous; lemmas finely muriculate between the veins, keel and marginal veins glabrous below; plants from Durango ………………………………………….. ……………………….11a. Poa matris-occidentalis subsp. matris-occidentalis Sheaths of lower leaves retrorsely scabrous to puberulent; collars ciliate; lemmas densely scabrous between the veins, keels and marginal veins puberulent below; plants from southern Chihuahua ………………………………………………. ……………………………….11b. Poa matris-occidentalis subsp. mohinorensis?Revision of Poa L. (Poaceae, Pooideae, Poeae, Poinae) in Mexico: …11a. Poa matris-occidentalis subsp. matris-occidentalis http://species-id.net/wiki/Poa_matris-occidentalis_matris-occidentalis Figs 10 A , 11 C Description. Leaf sheaths smooth, glabrous; collars glabrous; ligules abaxially glabrous. Lemma keel and marginal veins glabrous, between veins muriculate. Lodicules 0.3?.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?200 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., B. 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?2’31.1″N, 104?6’53.0″W, 3136-3348 m, 9 Sep 2006, P.M.Peterson 20011 F.S chez-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.11b. Poa matris-occidentalis subsp. mohinorensis Soreng P.M. Peterson, Sida 22(2): 911, f. 1d, 2a . 2006 http://species-id.net/wiki/Poa_matris-occidentalis_mohinorensis Figs 10 D, 11 A, B Type: SNDX-275 cancer Mexico, Chihuahua, Municipio de Guadalupe y Calvo, Sierra Madre Occidental, N side of Cerro Mohinora, ca. 13 mi SW of Guadalupe y Calvo, open pine-fir woods with scattered spruce, nearly vertical, N facing rock wall, very moist with many bryophytes and rich herbaceous flora, 25?57’N, 107?03′ W, 2950 m, 20 Aug 1988, G.Nesom A.McDonald 6475 (holotype: TEX!; isotype: ARIZ!). Description. Leaf sheaths retrorsely scabrous to puberulent; collars ciliate; ligules abaxially puberulent. Lemma keel and marginal veins proximally puberulent, between veins densely scabrous. Lodicules 0.75 mm long, broadly ovate with a broad lateral lobe. Distribution. This subspecies is known only from the Sierra Mohinora, Chihuahua. Ecology. The subspecies is found on moist rocky ledges and cliffs associated with Juniperus, Pinus, Abies, Picea, Holodiscus, Silene, Cerastium, Deschampsia cespitosa (L.) P. Beauv., Bromus carinatus, Muhlenbergia vaginata Swallen, and M. cenchroides; fromRobert J. Soreng P.Phological connections. Key to the subspecies of Poa matris-occidentalis 1 Sheaths of lower leaves smooth, glabrous; collars smooth or with a few hooks, glabrous; lemmas finely muriculate between the veins, keel and marginal veins glabrous below; plants from Durango ………………………………………….. ……………………….11a. Poa matris-occidentalis subsp. matris-occidentalis Sheaths of lower leaves retrorsely scabrous to puberulent; collars ciliate; lemmas densely scabrous between the veins, keels and marginal veins puberulent below; plants from southern Chihuahua ………………………………………………. ……………………………….11b. Poa matris-occidentalis subsp. mohinorensis?Revision of Poa L. (Poaceae, Pooideae, Poeae, Poinae) in Mexico: …11a. Poa matris-occidentalis subsp. matris-occidentalis http://species-id.net/wiki/Poa_matris-occidentalis_matris-occidentalis Figs 10 A , 11 C Description. Leaf sheaths smooth, glabrous; collars glabrous; ligules abaxially glabrous. Lemma keel and marginal veins glabrous, between veins muriculate. Lodicules 0.3?.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?200 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., B. 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?2’31.1″N, 104?6’53.0″W, 3136-3348 m, 9 Sep 2006, P.M.Peterson 20011 F.S chez-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.11b. Poa matris-occidentalis subsp. mohinorensis Soreng P.M. Peterson, Sida 22(2): 911, f. 1d, 2a . 2006 http://species-id.net/wiki/Poa_matris-occidentalis_mohinorensis Figs 10 D, 11 A, B Type: Mexico, Chihuahua, Municipio de Guadalupe y Calvo, Sierra Madre Occidental, N side of Cerro Mohinora, ca. 13 mi SW of Guadalupe y Calvo, open pine-fir woods with scattered spruce, nearly vertical, N facing rock wall, very moist with many bryophytes and rich herbaceous flora, 25?57’N, 107?03′ W, 2950 m, 20 Aug 1988, G.Nesom A.McDonald 6475 (holotype: TEX!; isotype: ARIZ!). Description. Leaf sheaths retrorsely scabrous to puberulent; collars ciliate; ligules abaxially puberulent. Lemma keel and marginal veins proximally puberulent, between veins densely scabrous. Lodicules 0.75 mm long, broadly ovate with a broad lateral lobe. Distribution. This subspecies is known only from the Sierra Mohinora, Chihuahua. Ecology. The subspecies is found on moist rocky ledges and cliffs associated with Juniperus, Pinus, Abies, Picea, Holodiscus, Silene, Cerastium, Deschampsia cespitosa (L.) P. Beauv., Bromus carinatus, Muhlenbergia vaginata Swallen, and M. cenchroides; fromRobert J. Soreng P.
