Proc. Acad. Nat. Sci. Philadelphia 4: 18. 1848
sw United States, nw Mexico.
Nemacaulis is allied to Eriogonum subg. Ganysma and especially E. gossypinum. Like that species, N. denudata has flowers embedded in a dense mass of hairs, which is the only significant feature that the two have in common aside from being annuals, generally spreading in habit, and having rather densely pubescent stems and leaves. The flowers in Nemacaulis are arranged in glomerules, a feature unique in Eriogonoideae. The involucre is markedly different, being composed of several whorls of bracts, each of which subtends a flower. In this and all the other members of Eriogoneae, modification of the involucre appears to be a significant factor in the evolution of distinctive genera. In Nemacaulis, the entire glomerule is dispersed by on-shore breezes along the coast, an effective transport mechanism for the tiny seeds. Entire glomerules may be trapped in moist pockets of sand, thereby positioning several seeds in a favorable location. In the rapidly evolving derived annuals of Eriogonineae, any selective advantage is quickly adopted and survival enhanced in the rather harsh environment, where members of the subtribe abound.
|Author||James L. Reveal +|
|Common name||Cottonheads +|
|Distribution||sw United States + and nw Mexico. +|
|Etymology||Greek nema, thread, and Greek kaulos, stem +|
|Publication title||Proc. Acad. Nat. Sci. Philadelphia +|
|Publication year||1848 +|
|Source xml||https://email@example.com/aafc-mbb/fna-data-curation.git/src/f50eec43f223ca0e34566be0b046453a0960e173/coarse grained fna xml/V5/V5 921.xml +|
|Synonyms||Eriogonum sect. Nemacaulis +|
|Taxon family||Polygonaceae +|
|Taxon name||Nemacaulis +|
|Taxon parent||Polygonaceae subfam. Eriogonoideae +|
|Taxon rank||genus +|
|Volume||Volume 5 +|