Boerhaavia

Boerhaavia
Boerhaavia coulteri
Epple & Epple



Boerhaavia wrightii
UofAz 2609



Boerhaavia coccinea UofAz

Boerhaavia:
Spiderling pollen is an interesting contrast to last month's grain of the month, Abronia. Sand verbena is tricolpate and reticulate, but spiderling is periporate and echinate. The Nyctaginaceae family is a classical example of "eurypalynous" plant-family pollen morphology. Although there is consistency within genera, there is great differences among genera. Boerhaavia pollen is large ca. 40 - 70 µm. Its distinguishing characters arsparselarge, sparce (6-12) pores that are often covered by prominent spines, which are interspersed among "pustules" (annulate pores) whose similar is similare to that of the spines, or smaller. The surface is smooth between the spines and "pustules," but a complex, rugulate, pattern is formed by the collumellae (?) below the tectum, visible in light micrographs.

Nyctaginaceae genera with similar pollen include Acleisanthes (spines less prominent, stronger "rugulate" pattern), Allionia (the large pores [not pustules] are smaller), Annulocaulis (large [> 100 µm] grain with relatively smaller "large pores"), Commicarpus (short spines [verrucae]), Mirrabilis (spines less prominent [very similar to Acleisanthes]), Selinocarpus (spines less prominent [very similar to Acleisanthes]).

Plants:
Family Nyctaginaceae
Boerhaavia (spiderling) plants are low, much-branched, thin stemmed plants, often with sticky hairy stems and leaves. The flowers are pink, white, or purple; borne in small cylindrical to umbellate inflorescences. The leaves arsparsely and denselyly to densly hairy. Boerhaavia is a common weed, frequent on vacant lots and along roadsides. Worldwide distribution in the warm regions of both hemispheres.

Pollen light micrograph:
The large grain is difficult to photograph, but the distinguishing pores and spines are easily distinguished through L-O analysis. However, the complex structure of the columella and the thin tectum somewhat obscure the "pustules."

Pollen scanning electron micrograph (SEM)
Minute "pustules" can be seen that are not apparent to light microscopy.

Production and Dispersal:
Spiderling is an insect-pollinated species with generally poor production and dispersal, but in disturbed habitats the plant is so abundant that pollen frequency in surface samples may exceed 20%.

Preservation:
Good, the walls are thick.

Fossil Occurrence:
Late Quaternary. This is one of the more common "disturbance indicators" in Southwestern Archeological Palynology (Fish, 1985)

References:
  • Epple, A.O. and Epple L.E. 1995.
    A field guide to the plants of Arizona. Falcon, Helena Montana, 347 pp.
  • Fish, S.K. 1985.
    Prehistoric disturbance floras of the lower Sonoran Desert and their implications. AASP Foundataion Contribution Series 16; 77-88.
  • Nowicke, J.W. 1970.
    Pollen morphology in the Nyctaginaceae. I. Nyctagineae (Mirabileae). Grana 10: 79-88.
  • Nowicke, J.W. and Luikart, T.J. 1970.
    Pollen morphology in the Nyctaginaceae. II. Colignonieae, Boldoeae, and Leucastereae. Grana 10: 79-88.

Links
Owen Davis 4/02