The Texas sleepy daisy
The species includes two subspecies (ssp. drummondii and ssp. texanum with two varieties; var. orientalis and var. texanum confined to southern Texas). The plants are usually less than 0.5 m tall but a "giant" plant was found in 1972.
J.C. Semple, 1972, Texas
The species has been offered in the past in seed catalogues and collections of escaped cultivated plants have been made from areas greatly out of the range of distribution (e.g., Northern California and North Africa).
The species is notable for its accessory B chromosome first discovered and investigated by Witkus and co-workers in the 1950's and 1960's. More recent studies done by John C. Semple are listed below.
A fourteen year long study of variation in the frequency of plants with and without B chromosomes was conducted in southwestern Oklahoma in and around Quartz Mt. State Park. More than a thousand individuals were sampled. The conclusion of all the research was that these extra chromosomes were "endo-parasitic" containing genes for their own propagation but otherwise being of little or no value to the the "host" plant. The B chromosomes may be the remnants of the ancestral fifth pair of chromosomes.
Publications by J.C. Semple on Xanthisma
SEMPLE, J.C. 1972. The behavior of B-chromosomes in Xanthisma texanum DC.: a non-random phenomenon. Science 175: 666.
SEMPLE, J.C. 1972. The cytology, flavonoid chemistry and systematics of the Texas Sleepy Daisy Xanthisma texanum DC. (Asteraceae). Ph.D. Doctoral Dissertation, Washington University - St. Louis.
SEMPLE, J.C. 1973. Chiasma formation in the sub-metacentric B-chromosome of Xanthisma texanum DC. Canad. J. Genet. Cytol. 15: 871-873.
SEMPLE,
J.C.
1974a.
The
phytogeography
and
systematics
of
Xanthisma
texanum
DC.
(Asteraceae):
proper
usage
of
infraspecific
categories.
Rhodora
76:
1-19.
SEMPLE,
J.C.
1974b.
The
geographical
distribution
of
B-chromosomes
of
Xanthisma
texanum
DC.
(Asteraceae).
I.
Survey
of
the
range.
Amer.
J.Bot.
61:995-1001.
SEMPLE,
J.C.,
and
J.E.
AVERRETT.
1975.
Flavonoid
variation
in
Xanthisma
texanum:
infrapopulation
and
interpopulation
variation.
Biochem.
Syst.
Ecol.
3:
11-14.
SEMPLE,
J.C.
1976.
The
cytogenetics
of
Xanthisma
texanum
DC.
(Asteraceae)
and
its
B-chromosomes.
Amer.
J.
Bot.
63:
388-398.
SEMPLE,
J.C.
1989.
Geographical
distribution
of
B
chromosomes
of
Xanthisma
texanum
(Compositae:
Astereae).
II.
Local
variation
within
and
between
populations
and
frequency
variations
through
time.
Amer.
J.
Bot.
76:
769-776.
SEMPLE,
J.C.,
and
J.G.
CHMIELEWSKI.
1989.
Studies
on
the
effects,
or
lack
thereof,
of
B
chromosomes
on
the
morphology
and
pollen
viability
in
wild
and
cultivated
plants
of
Xanthisma
texanum
(Compositae:
Astereae).
Canad.
J.
Bot.
67:
1157-1160.
Last updated 14 November 2013 by J.C. Semple
© 2013 J.C. Semple, including all photographs unless otherwise indicated