Pollen Morphology of the Oklahoma Endemic PlantsLeavenworthia aurea(Brassicaceae/Cruciferae) andPhlox pilosaSubsp.Longipilosa(Polemoniaceae), With Special Reference To Their Natural History

Abstract

The morphology, taxonomy, ecology, distribution, and conservation status of the Oklahoma endemics, Leavenworthia aurea (Brassicaceae/Crucifereae) and Phlox pilosa subsp. longipilosa (Polemoniaceae) Pennell, are reviewed and supplemented with original pollen morphological descriptions that include comparisons to related taxa. These descriptions are considered extensions of the original taxonomic descriptions. Leavenworthia aurea is a glabrous winter annual found on limestone glades in Choctaw and McCurtain counties. The taxon is considered imperiled, with Natural Heritage rankings of G2S2. The pollen has three colpi with a reticulate surface enclosing polygonal lumina (openings within reticulations on the pollen surface) with lengths varying from 0.5–2.5 µm, that are either empty or contain inclined free standing columellae approximately 0.5–0.8 µm in height. Granules less than 0.5 µm in diameter also occur in some lumina, but are most common in the colpus. The reticulate surface of Leavenworthia pollen is similar to other Cardamineae, as well as to the pollen of other members of the Brassicaceae. Phlox pilosa subsp. longipilosa, found on granitic soils in the Quartz and Wichita mountains of Greer and Kiowa counties, is a branching spring perennial ranging from 20.0–45.0 cm in height. Like L. aurea, it is considered to be imperiled, with a Natural Heritage ranking of G2S2. Phlox pollen morphology has been broadly characterized but has not been described in P. pilosa subsp. longipilosa. The pollen of P. pilosa subsp. longipilosa is pantoporate and reticulate, with enclosed polygonal lumina often exceeding 5.0 µm. The exine (pollen surface) is multireticulate because all lumina, except those containing pores, enclose smaller reticulate networks composed of thin rods of sporopollenin. In porate lumina, sporopollenin rods are curved, with one end attached to the surrounding ridges, as they are in non-porate lumina; the other end either hangs freely above the pores or is attached to the pore margins. Pollen morphology is similar to well-established Phlox pollen types.