1. Leaves simple, not at all dissected.....T. canadense
In Texas, an easily recognized species because of its undissected leaves.
McClintock and Epling (1946) recognized 3 sympatric varieties within this species, none of which appears sustainable, the species being extremely variable throughout its range, both as to leaf shape and pubescence. Correll and Johnston (1970), however, following McClintock and Epling, recognized two of these (var. canadense and var. occidentale) as occurring in Texas, distinguishing between them by characters which do not seem to define regionally meaningful categories.
Named for Canada, where first collected.
Much resembling T. cubense but the leaves more deeply cleft, the foliage and stem usually to some extent pubescent.
McClintock and Epling (1946) recognized this taxon as part of their concept T. cubense subsp. laevigatum (= T. laevigatum Vahl.), but the latter is typified by South American material quite different from that of T. coahuilanum. Occasional plants from the trans-Pecos approach those of the more eastern T. cubense and a more conservative treatment might treat these two taxa as but varietally distinct.
Named for the Mexican state of Coahuila where the species is especially common.
McClintock and Epling (1946) recognized 5 subspecies under this taxon, 3 of these occurring in Texas. We recognize the several Texas elements as species, finding little, if any, intergradation between them. In addition, we cannot accept their treatment of T. cubense as having an amphitropical distribution, with two of the subspecies (cordobensis and cubensis) occurring in temperate South America. We would treat both of the latter as specific taxa.
Named for the island of Cuba where first collected.
Small annual or short-lived perennial herbs to 30 cm high, the stems much branched from the base; stems and leaves moderately hirsute with spreading hairs.
McClintock and Epling (1946) treated this well-defined species as a subspecies of their broad concept of T. cubense, while Jepson (1925: Man. Fl. Pl. Calif. 861) treated it as a variety of that species. We believe the taxon to be specifically distinct; T. depressum occurs in a distinct ecogeographic region and does not appear to intergrade with the more eastern mesic species, T. cubense.
Named for the small habit or depressed stature.
Low perennial herbs 10-20 cm high forming small colonies by rhizomatous offshoots; corollas white, relatively large with very pronounced lower lips.
A very distinct species, not easily confused with another because of its low habit and large flowers.
Named for its laciniate or deeply incised leaves.