A NEW COMBINATION IN 'BOUTELOUA' (POACEAE)

2 Pages·1996·1.2 MB·English

by  Joseph K Wipff

NEW
A COMBINATION
BOUTELOUA
(POACEAE)
IN
JOSEPH WIPFF STANLEY JONES
K. and D.
(BRCH)
Herbartum
Botanical Research Center
Box 6717
P.O.
TX
77805-6717,
Bryan, U.S.A.
ABSTRACT
&
Wipff una
S.D. Jones. Se ofrece clave
Bouteloua hirsuta M. Lagasca Segura subsp. pectinata (H. Featherly)
y
J.
&
Wipff S.D. Jones, comb, et Stat. nov. Basionym: Bouteloua pectinata H.
hmuta
Fearherly, Bot. Gaz. 91:103. 1931. Bouteloua vnt. pectinata (H. Featherly) V.
UNITED
STATES. Oklahoma. Comanche
Cory, Rhodora 38:405. 1936. Type: Co.:
Aug
near Fort 17 1929, B. English 71 (holotype: US).
Sill,
been recognized
Bouteloua pectinata, closely related to B. hirsuta, has at
taxonomic Roy and Gould (1971) and Gould (1975, 1979)
various ranks:
recognized this taxon as a distinct species; Cory (1936) recognized it as a
variety of B. hirsuta; and Hitchcock (1935) and Chase (1951) treated it as a
synonym of B. hirsuta without any infraspecific rank. The two taxa can be
&
Gould
(Roy
distinguished by the following characters 1971):
lowermost rudimentary
Tuft of trichomes present at the base of the floret;
1.
25-40
nflorescence axis c
A and by Roy and Gould
biosystematic study of B. pectinata B. hirsuta
971) resulted in the following conclusions: 1) B. pectinata is restricted to
undisturbed calcareous and most frequent
ell-drained, relatively soils
is
Comanche
from Pontotoc and
limestone outcrops, occuring
thin-soiled
1
)unties, Oklahoma, south to Uvalde County, Texas; 2) Bouteloua hirsuta.
109-
found wide
in a variety of habitats, widely distributed and occurs from
is
New
Wisconsin and North Dakota, south
Illinois to to Louisiana, Texas,
Mexico, Arizona, southern California, and northern Mexico; the mor-
3)
phological uniformity of B. peainata, In = 20 populations
contrasts strik-
ingly to the morphological variability observed in the diploid plants 2n =
hmuta
20, of B. hirsuta. Usually associated with diploid B. are plants with
widely varying chromosome numbers, 2n =
e.g. 22, 24, 26, 28, 30, 32, 34,
36, 40, 42, 43, 44, 45, 46, 48, 50, 52, 53, 54, 56, 58, and 60 (Roy 1968);
where two
4) populations of the taxa are sympatric, swarms of putative
hybrid plants are found that are intermediate in some or of the
all critical
morphological and most
characteristics; for the part, these putative hy-
5)
swarms
found
brid are only along the margins of typical B. pectinata
sites
(when
populations of B. hirsuta are also present). Sites in Kendall County,
Texas appear to be representative of the ecological distribution and separa-
tion of the two taxa. Roy and Gould (1971) stated, "Throughout this area
two
the species, B. hirsuta and B. were intermingled
pectinata, in slightly dis-
way
turbed road right of sites. Bouteloua hirsuta predominated at the base of
the slopes and in the guUeys and ditches, and B. was most
\sic\ pectinata
abundant on and
the ledges hilltops. Intermediate plants were abundant."
From
these data, B. pectinata restricted in geographic distribution,
is its
occupies a specific ecological site, and generally ecologically allopatric
is
and morphologically distinct from B. hirsuta. However, there are putative
hybrid swarms at the boundary where the two taxa come in contact. These
swarms show
an integration of morphological between two
characters the
taxa indicating a lack of complete reproductive These data war-
isolation.
rant the recognition of B.
pectinata at the subspecific rank.
We
W.E.
are grateful to Fox, (TAES), Stephan Hatch (TABS),
III L.
AWPMRU),
(USDA,
Gretchen D. Jones and W. Morden
Clifford
for re-
ArtvisionolAS
CllASC,A 1951 Ilitchcocks manual of the i^nsses «1 the U:
USDA
US
2nd
ed Misccll niKuis PliMi. 200 Government
ition Prin
V nmns
New
Cory, 19-.6 ind ikw eomhin ions h)r Texas plants Rhodora
3
it
rW
Gould, 19^^ The ^usso utkx kxis AcVM
University
Press, Colie^
is
FW
Gould, 19^9 The ^enus 6 (Puaee Ann Missouri Bot Gard
//',//// ic) 6
AS
U D
Hitchcock, Manual
19^)5 oi the grasses of the United Stares S
i
U
D
neous Publication 200 S Governmenr Printing Olhte, Washington,
G
A
Ro\, P 1968
systematic study of the Bmitdoiia hnuUa-Boutdoiia
petttna
A&M
D
Ph
dissertation, Texas University College Station
W
G
Roy, P and F Gould 97
Biosystematic
investigations of Biwttloua hi
1
1
Gross morphology Southw ^77-387
pectinata Naturalist 15
I