Poa matris-occidentalis mohinorensis Soreng & P.M. Peterson, Sida 22(2): 911, f. 1d, 2a-b. 2006

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 : 34-35

11b. Poa matris-occidentalis mohinorensis Soreng & P.M. Peterson, Sida 22(2): 911, f. 1d, 2a-b. 2006 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 Muhlenbergia cenchroides ; from 2950 -3300 m (see below, Correll’s estimation is too high according to the geodetic mark at the top of the peak). Flowering August to October.

Specimens examined.

Mexico. Chihuahua: Sierra Mohinora, near Cumbre Mohinora, 25°57'34"N, 107°03'49"W, 3250-3300 m, 13 Sep 2006, P.M.Peterson 20048, F. Sánchez-Alvarado & E.P. Gómez-Ruíz (US); ditto, 20049 (US); ditto, on summit, 10,000-12,000 ft [3050-3660 m], 16-17 Oct 1959, D.S.Correll 23177 & H.S.Gentry (LL).

Discussion.

When the second author visited the type locality in 2006, the habitat within 5 km of the peak was found to be quite disturbed by grazing and logging. The holotype was initially determined as Poa tracyi "vel. aff." by J.R & C.G. Reeder in 1989).

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).