Parks's jointweed

Herbs, annual, gynodioecious, 5.5-15 dm. Stems erect, usually branched proximally and distally, sometimes simple, glabrous. Leaves fugaceous; ocrea margins ciliate; blade linear, (0.9-)4-10.5(-15) × 0.3-0.8 mm, base barely tapered, margins hyaline, apex obtuse, glabrous. Inflores-cences 2-6(-8) mm; ocreola not encircling rachis, sides and bases adnate to rachis, apex acuminate. Pedicels spreading in anthesis, spreading to reflexed in fruit, 0.4-1.3 mm, much longer than subtending ocreola. Flowers bisexual or pistillate; outer tepals loosely appressed to spreading in fruit, white, distal portion of midrib often greenish, obovate to elliptic, 0.5-0.9 mm in anthesis, margins obscurely erose; inner tepals loosely appressed in anthesis and fruit, white, obovate to elliptic, 0.6-1.4 mm in anthesis, margins entire to erose; filaments dimorphic; anthers yellow or pink; styles and stigmas 0.1-0.3 mm in anthesis. Achenes exserted, yellow-brown, 3-gonous, 1.7-2.1 × 1.3-1.6 mm, shiny, smooth. 2n = 36.

Flowering Jul-Oct. Deep, loose sand in oak woodlands, sandy rangeland, disturbed sites; of conservation concern; 100-200 m; Tex.

Polygonella parksii is known from eight counties in south and east-central Texas. It appears to belong to a clade including P. articulata, P. americana, and P. myriophylla (P. O. Lewis and D. J. Crawford 1995).