mesquite flower
by Owen Davis

APMRU # 106
Prosopis glandulosa APMRU # 106

UofAz 1747
Prosopis velutina UofAz 1747

Prosopis velutina UofAz 1747 Mesquite pollen is ca. 34 (P) x 24 (E) µm and tricolporate. Its distinguishing character is the circular pore (endopore) in center of the furrow (visible in LM). The walls abruptly bend into the furrows, creating a "margo". The grain has a small polar area. Occasional small elements are visible in the ends of the furrows. Mesquite pollen sculpture is "rough" (reticulate - "punctate"). The shape, furrows, and sculpture of the pollen of ironwood (Olnea tesota) is very similar, but its pore is thinned, not thickened, in the intine and the pore diameter is greater than the width of the furrow.

Fam. Leguminosae (Fabaceae) Mimosaceae
Prosopis (mesquite) are shrubs and trees, widespread in arid regions of the New World, Africa, and southwest Asia. (Deciduous) leaves bipinnately compound, with two divergent leaflets. Paired thorns at the base of each (prominent and persistent) leaf-base. Flowers small, perfect with excerted stamens, born in compact elongate inflorescences. Heart wood is red.

Pollen light micrograph:
The distinctive endopore is visible on most grains, but may be disrupted in shriveled or broken grains. The protruding pore membrane is removed by acetolysis. The grains often appear "angular" and bent at the equator with straight furrows between the equator and pole. The distinct "margo" and small polar area are also useful identifying characters.

Pollen scanning electron micrograph (SEM)
The endopore is not visible, but protruding pore membranes often are.

Production and Dispersal:
An insect (beetle?) pollinated species with generally poor production and dispersal. However, since mesquite is a tree, its pollen does become airborne, and may be present in small amounts in surface samples (< 5%, Davis, 1995) and fossil samples.

Good, the walls are thick.

Fossil Occurrence:
Late Quaternary. However, given its amphitropical and amphi-Atlantic distribution, Prosopis likely originated during the early Tertiary, so the absence of mesquite pollen in the pre-Quaternary pollen record likely results from its low production and dispersal.

  • Davis, O.K. 1995..
    Climate and vegetation patterns in surface samples from arid western U.S.A.: Application to Holocene climatic reconstructions. Palynology. 19:97-120.

Owen Davis 12/02