Texas Sunflower

The taxa of Helianthus praecox were placed as subspecies of H. debilis by C. B. Heiser (1956). They were separated later, primarily on the basis of crossing results (Heiser et al. 1969). The subspecies appear to form a grade between H. debilis and H. petiolaris.

Annuals, 40–150 cm. Stems erect to ± procumbent, hispid, hispid-hirsute, or hirsute. Leaves mostly cauline; mostly opposite; petioles 5–9 cm; blades deltate to ovate (sometimes constricted near middles, subsp. praecox) , 3–9 × 2–7 cm, bases cordate , cuneate, or trun-cate, margins serrate to serrulate, abaxial faces hirsute to hispid, usually not gland-dotted. Heads 1–3. Peduncles 15–40 cm. Involucres hemispheric, 13–18 mm diam. Phyllaries 30–39, lanceolate, 9–15 × 2–4 mm, apices short-attenuate to short-acuminate (subsp. praecox), abaxial faces hispidulous to hispid-hirsute. Paleae 6.5–8 mm, 3-toothed (middle teeth acuminate, equaling or slightly surpassing discs, apices puberulent or bearded, hairs whitish). Ray florets 11–16; laminae 16–26 mm. Disc florets 35+; corollas 5–6 mm, lobes reddish; anthers dark, appendages purplish red (style branches reddish). Cypselae 2.5–3.3 mm, ± villous; pappi of 2 aristate scales 1.2–1.5 mm.

Helianthus praecox is a North American species of sunflower known by the common name Texas sunflower. It is endemic to Texas. Most of the populations are either along the Gulf Coast or in the Río Grande Valley.

Helianthus praecox grows on sandy soils and coastal prairies. It is an annual herb up to 150 cm (60 inches or 5 feet) tall. One plant usually produces 1-3 flower heads, each containing 11-16 yellow ray florets surrounding 35 or more red or purple disc florets.

Subspecies Helianthus praecox subsp. hirtus (Heiser) Heiser - near Carrizo Springs in Dimmit County Helianthus praecox subsp. praecox - sandy soils along the coast in Galveston County + Brazoria County Helianthus praecox subsp. runyonii (Heiser) Heiser - Coastal prairies (from Calhoun County to Cameron County) and Río Grande Valley (from Webb County to Cameron County)