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
Author
Soreng, Robert J.
Department of Botany, National Museum of Natural History, Smithsonian Institution Washington, DC, 20013 - 7012, USA
Author
Peterson, Paul M.
Department of Botany, National Museum of Natural History, Smithsonian Institution Washington, DC, 20013 - 7012, USA
text
PhytoKeys
2012
2012-08-06
15
1
104
http://dx.doi.org/10.3897/phytokeys.15.3084
journal article
http://dx.doi.org/10.3897/phytokeys.15.3084
1314-2003-15-1
FF9AC356FFDAFB26FF95FFE3FFA1520C
576134
8c.
Poa fendleriana longiligula (Scribn. & T.A.Williams) Soreng, Great Basin Naturalist 45(3): 408. 1985.
Fig. 8 H-I
Poa longiligula
Scribn. & T.A.Williams, Circ. Div. Agrostol. U.S.D.A. 9: 3. 1899.
Paneion longiligulum
(Scribn. & T.A. Williams) Lunell, Amer. Midl. Naturalist 4: 222. 1915.
Poa fendleriana
var.
longiligula
(Scribn. & T.A.Williams) Gould,
Madrono
10(3): 94. 1949. Type: USA, Utah, Washington Co., Silver Reef, gravel, 3500 ft [1070 m], 3 May 1894,
M.E.Jones 5149
(holotype: US-278727!; isotypes: MO!, NY-431282!, OSC!, US-922924!).
Description.
Leaf
collars smooth to scabrous near the throat; ligules of middle cauline leaves (1.5-)1.8-18 mm long, decurrent, abaxially smooth or lightly scabrous, upper margin usually smooth, glabrous, apices obtuse to acuminate; sterile shoot blades usually scabrous or softly puberulent adaxially.
Spikelet
rachilla internodes usually sparsely hispidulous or sparsely softly puberulent; lemmas long villous on keels and marginal veins and sometimes intermediate veins, between veins glabrous or softly puberulent (sometimes densely so); palea keels and between keels sometimes puberulent.
Lodicules
0.85 mm long. 2
n
= 56.
Distribution.
The subspecies occurs in North America, southwestern Canada, western USA, and in Baja California, Mexico.
Ecology.
Where their ranges overlap
Poa fendleriana
subsp.
longiligula
is fairly restricted to elevations below
Poa fendleriana
subsp.
fendleriana
but where there is some winter snow. In Mexico this subspecies is strictly pistillate, apomictic, and distributed between 1300-1900 m. Flowering in spring.
Specimens examined.
Mexico.
Baja California:
Hansen's
Ranch, 21 Jun 1885, C.R.Orcutt 1276 (DS♀, DS♀, US). 63 mi SE of Ensenada, 2-3 mi upstream of Rincon, 4.5 mi NE of Santa Catarina, canyon, 4300 ft [1310 m] 22 Apr 1962, R.E.Broder 772 (DS♀, US♀). 4 1/2 mi S of Portezuelo de Jamau, N of Cerro 1905, ca.
31°34'N
,
115°36'W
, 1775 m, 20 Apr 1974, R.Moran 21226 (CAS♀, ARIZ♀, TAES♀, US). Sierra Juarez, El Progresso, ca.
32°17'N
,
115°56'W
, 1450 m, 24 May
1975
, R.Moran 22044 (TAES♀); ditto, N slope just below summit of Cerro Jamau, ca.
31°34'N
,
115°35.5'W
, 1890 m, 23 May 1976, R.Moran 23257 (TAES♀); ditto, in steep north slope of Cerro Taraizo, southernmost peak of range, ca.
31°21.75'N
,
115°31'W
, 1550 m, R.Moran 23007 (TAES♀, ARIZ♀, US); ditto, vicinity of Rancho La Mora,
32°01'N
,
115°47'W
, 12 Apr 1987, C.Brey 192 (TAES♀). Rancho El Topo, 2 May 1981, A.A.Beetle & R.Alcaraz M-6649 (ARIZ♀, WYAC♀). Sierra San Pedro
Martir
,
Canon
del Diablo,
31°00'N
,
115°24'W
, 1700 m, 6 May 1978, R.Moran 25626 (TAES♀).
Discussion.
This taxon was accepted as
Poa longiligula
by
Espejo Serna et al. (2000)
. Some plants in Baja California of this subspecies are intermediate to
Poa fendleriana
subsp.
fendleriana
, but in general the longer smoother margined ligules and puberulent rachillas are diagnostic. Where the two taxa occur in the same area
Poa fendleriana
subsp.
longiligula
occurs in more xeric habitats, and
Poa fendleriana
subsp.
fendleriana
is found in higher elevations.