Voila ! Buffalo Bur

Solanum rostratum is a species of nightshade (genus Solanum) that is native to the United States and northern and central Mexico.[1] Common names include buffalo bur, spiny nightshade, Colorado bur, Kansas thistle, Mexican thistle, and Texas thistle.

It is an annual, self-compatible herb that forms a tumbleweed.[2] Individual plants reach 1–1.5 m (3.3–4.9 ft) tall, have once or twice pinnatified leaves, and abundant prickles on the stems and leaves. It produces yellow flowers with pentagonal corollas 2–3.5 cm (0.79–1.4 in) in diameter and weakly bilaterally symmetric.[3] In its native range S. rostratum is pollinated by medium- to large-sized bees including bumblebees.[4]

S. rostratum flowers exhibit heteranthery, i.e. they bear two sets of anthers of unequal size, possibly distinct colouration, and divergence in ecological function between pollination and feeding.[5] The fruit, a berry, is enclosed by a prickly calyx. The seeds are released when the berries dry and dehisce (split apart) while still attached to the plant.

This species represents one of the latter scientific interests of famed biologist Charles Darwin, who just over a week prior to his death had ordered seeds from a colleague in America, so as to investigate their heteranthery, a topic he was interested in.[6]

S. rostratum is the ancestral host plant of the Colorado potato beetle, Leptinotarsa decemlineata, but this pest adopted the potato, Solanum tuberosum as a new (and more succulent) host, a fact first reported in eastern Nebraska in 1859. It then expanded its range rapidly eastward on potato crops in the next two decades.[7]

References

^ a b “Solanum rostratum Dunal”. Germplasm Resources Information Network. United States Department of Agriculture. 2008-11-06. Retrieved 2010-06-07.
^ Louis Hermann Pammel (1903). Some Weeds of Iowa. Experiment Station, Iowa State College of Agriculture and the Mechanic Arts. page 477
^ Whalen, M.D. 1979. Taxonomy of Solanum section Androceras. Gentes Herbarum 11: 359-426.
^ Bowers, K.A.W. 1975. The pollination ecology of Solanum rostratum (Solanaceae). American Journal of Botany 62: 633-638.
^ Vallejo-Marin, M., Manson, J.S., Thomson, J.D. and Barrett, S.C.H. 2009. Division of labour within flowers: Heteranthery, a floral strategy to reconcile contrasting pollen fates. Journal of Evolutionary Biology. 22: 828-839.
^ Buchmann, S.L. (1983) Buzz pollination in angiosperms. In: Jones, C.E. and Little, R.J. eds. Handbook of experimental pollination biology. New York: Van Nostrand Reinhold. pp. 73-113
^ Riley CV. 1876. Potato Pests. New York, Orange Judd Co., 108pp

Division of labour within flowers: heteranthery, a floral strategy to reconcile contrasting pollen fates.

Vallejo-Marín M, Manson JS, Thomson JD, Barrett SC.

Source

Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, Canada. mario.vallejo@stir.ac.uk

Abstract

In many nectarless flowering plants, pollen serves as both the carrier of male gametes and as food for pollinators. This can generate an evolutionary conflict if the use of pollen as food by pollinators reduces the number of gametes available for cross-fertilization. Heteranthery, the production of two or more stamen types by individual flowers reduces this conflict by allowing different stamens to specialize in ‘pollinating’ and ‘feeding’ functions. We used experimental studies of Solanum rostratum (Solanaceae) and theoretical models to investigate this ‘division of labour’ hypothesis. Flight cage experiments with pollinating bumble bees (Bombus impatiens) demonstrated that although feeding anthers are preferentially manipulated by bees, pollinating anthers export more pollen to other flowers. Evolutionary stability analysis of a model of pollination by pollen consumers indicated that heteranthery evolves when bees consume more pollen than should optimally be exchanged for visitation services, particularly when pollinators adjust their visitation according to the amount of pollen collected.

Solanum rostratum

Solanum rostratum Dunal

Buffalobur nightshade, Buffalo bur

Solanaceae (Potato Family)

USDA Symbol: SORO

USDA Native Status: L48 (N), CAN 

Dense, golden-yellow prickles cover the stems and calyx of each yellow, star-like flower on this leafy weed.

The prickles on this highly toxic plant help to discourage grazing by livestock. An equally prickly species of about the same habit, Melonleaf Nightshade (S. citrullifolium), has blue-violet corollas.