TAXONOMY OF MEXICAN PODOSTEMACEAE

A taxonomic treatment of Podostemaceae in Mexico is presented, based o n herbarium study and extensive field collections. Five genera and eig ht species of Podostemaceae (including Tristichaceae) occur in Mexico: Marathrum Humb. & Bonpl. (M. rubrum Novelo & Philbrick, M. schiedeanu m (Cham.) Tul., M. tenue Liebm.), Oserya Tul. & Wedd. (O. coulteriana Tul., O. longifolia Novelo & Philbrick), Podostemum Michx. (P. ricciif orme (Liebm.) P. Royen), Tristicha Du Petit-Thouars (T. trifaria (Bory ex Willd.) Spreng.) and Vanroyenella Novelo and Philbrick (V. plumosa Novelo & Philbrick). More species occur on the Pacific slope (especia lly the states of Jalisco, Michoacan and Guerrero) than the Atlantic s lope. In Mexico, Podostemaceae occur predominantly in three main clima te types (A, hot and humid; B, dry; C, temperate and humid), and eight Mexican physiographic provinces. Podostemaceae are found primarily in river rapids that occur in the following vegetation types: oak-pine f orest, moist mountain forest, tropical rain forest, tropical subdecidu ous forest and tropical deciduous forest. (C) 1997 Elsevier Science B. V.