[Alluding to the Tamaulipan Desert region, to which the species is restricted]

Guy L. Nesom

Shrubs, (100–)200–300 cm (sometimes subscandent, climbing and sprawling over other plants). Stems erect or clambering, intricately branched (often brittle, glabrous or nearly so, not viscid). Leaves cauline; opposite; petiolate; blades usually 3-nerved from bases, deltate, margins toothed, faces puberulent to velutinous (not gland-dotted). Heads discoid, in corymbiform arrays. Involucres obconic to hemispheric, 5–7 mm diam. Phyllaries persistent, 30–35 in 2–3+ series, obscurely nerved, lanceolate to subulate, unequal (herbaceous to chartaceous or membranous). Receptacles convex to conic, epaleate. Florets 30–50+; corollas usually blue to lavender, sometimes white, throats narrowly funnelform (lengths 1.5–2 times diams.); styles: bases not enlarged, glabrous, branches linear-filiform. Cypselae prismatic, 5–6-ribbed, sparsely scabrellous; pappi persistent, of ca. 35 barbellate bristles in 1 series. x = 10.

Species 1: Texas, ne Mexico.

Lower Taxon

• Tamaulipa azurea (A. P. de Candolle) R. M. King & H. Robinson