EUPHORBIA GRAMINEA (EUPHORBIACEAE) NEW TO FLORIDA

2 Pages·1994·1.1 MB·English

by  Alan Herndon

—
A New
Martin, W.C. 1982. of
flora
I
litgesellschaft.
New
MDLEY. 1915. Flora of ^
Washington.
rinting Office,
NEW
GRAMINEA TO
EUPHORBIA (EUPHORBIACEAE)
FLORIDA
c^me southemFlonda.
Euphorbia graminea)sicq. apparently into
during 1980s weed John Popenoe found
the late as a in horticultural stock.
communica-
without
plants flowers in nurseries for several years (personal
but was not until Jan-Feb 1993 that Popenoe and independently
tion),
it I
found flowering populations ofE.grammea separated by several miles. Plants
new
of this species were found again, and in areas, during the of 1993
fall
so seems fair to regard the species as established in southern Florida.
it
cm
Euphorbia graminea an erect annual reaching 35 in height with leaves
is
cm
well separated along the stem and branches. Stem leaves are 2-4 long,
alternate and, on Florida plants seen, are ovate with undulate margins.
all
Leaves on the branches of the inflorescence are slightly shorter, opposite or
nearly so and narrowly elliptic. Cyathia are terminal or solitary in the axes
—
mm
A
number
of dichasia and about long. variable (1-4) of glands pro-
1 is
many
duced along the upper edges of the cyathium, with specimens having
two glands on the cyathium. Glands have white appendages that are about
The
equal in size to the glands. capsule held beneath the gland appendages
is
may
until maturity and not be apparent without close inspection. Mature
mm
about long and wider than
capsules are 3 long.
Euphorbia graminea widespread from southern Mexico northern South
to
is
America, and has weedy tendencies throughout this range. It shows consid-
erable variation in leaf shape and pubescence, leading to the proposal of
several subspecific groups. There no consensus on the validity of these
is
made
(Webster and Burch no attempt was
subspecific taxa 1968), so to
below
identify the Florida plants the specific level.
Within the genus Euphorbia (sens, E. graminea the lectotype species
lat.), is
(Wheeler been under
of the section Cyttarospermum 1943). It has also treated
the segregate genus Eumecanthus. This group characterized by petiolate
is
bumps
leaves and ecarunculate seeds with an areolate pattern of raised
covering the surface (Subils 1977).
made
All collections from Florida so far have been in cultivated sites.
Within
these cultivated areas, the Euphorbia evidently prefers bare patches.
Seeds are dispersed locally by the explosively dehiscent capsules, but the pri-
human
mary means of spread in southern Florida seems to be through trans-
grown
ornamental
port of plants, especially
field trees.
FLORIDA. Dade
Voucher specimens: Co.: weed in residential lawn, near Homestead, 28
Romney
Jan 1993, Herndon 3338 (FTG); weed at the Dave farm, Homestead, 5 Feb 1993,
Popenoe 2476 (FTG); growing in planted bed along the right-or-way of Old Cutler Road, ca.
1/4 mi S of Fairchild Tropical Garden, 20 Feb 1993, Popenoe 2480 (FTG); weed in potted
Aug
plant by residence, Perrine, 20 1993, Herndon 3346 (FTG).
am
grateful to John Popenoe for sharing his knowledge of the early
I
Alan
history of this species in Florida. Herndon, Department of Biological
EL
Florida International University, Miami, 33199, U.S.A.
Sciences,
REFERENCES
Subils, R. 1977. Las especies de Euphorbia de la Republic
Webster, G.L. and D. Burch 1968. Family Euphorb
97.
Panama, Part VI. Ann. Missouri Bot. Gard. 54:211-
Wheeler, The Eupho
L.C. 1943. genera of the living
30:456-503.