Agave


by Owen Davis


UofAz
Agave fossil APMRU


UofAz
Agave americana UofAz

Agave:
Agave (fam. Agavaceae) pollen is distinctive, but rare in most sedimentary and airborne samples. It can be recognized by its coarse reticulation, and broad operculum that covers ¼ of the pollen grain's surface.

Plants:
The agaves are a numerous (about 100 species) and economically important genus found in Arizona and Mexico. These monocots are characterized by a basal rosette of fleshy, thorny leaves. The flowers are produced on an erect woody inflorescence (up to 3 m!) ascending from the center of the rosette. The various species are pollinated by bats and birds (particularly humminbirds), and by various insects. For Indians, the plants were an important source of fibre and beverage, with 11 species used for mescal or tequila, a distilled beverage named after the town of Tequilla, Jalisco, Mexico, where it has been distilled for nearly 200 years. Agave tequilana Weber, is the primary source of commercial tequilla (Gentry, 1982). The larvae of the agave snout beetle (Scyphophorus acupunctatus) is the worm in the bottle. It is about 5 cm long when placed in the bottle and shrinks to about 1 cm long as the beverage ages.

Pollen light micrograph:
The grains are large 30 - 70 µm and elliptical (subspherical). The sculpture is per-reticulate (perforate tectate), the reticulum is coarse, with large collumella evident (LO analysis) beneath the muri, which are wider above the columella. Small lumina (~ width of muri) are occasionally present. The reticulum thins abruptly at the margins of the operculum. Sculptural elements are visible in bases of the lumina.

Agave americana UofAz

Pollen scanning electron micrograph (SEM)
The floors of the lumina are very rough in comparison to the smooth surface of the muri. The terminus of the operculum is distinct in this view (right).

Production and Dispersal:
Pollen of this zoophilous genus is found occasionally, in low abundance, in aquatic or archeological samples, but is sometimes common in packrat middens and bat guano.

Preservation:
Good.

Fossil Occurrence:
Eocene? (internet document, without reference)

References:
  • Gentry, H.S. 1982.
    Agaves of continental North America. University of Arizona Press. 670 p.
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Owen Davis 12/01