Experimental and Natural Hybrids in North American Typha (Typhaceae)

Abstract

Typha latifolia L., T. angustifolia L. and T. domingensis Pers. occupy distinct but overlapping ecological and geographic ranges. The plants are protogynous, self-compatible and rhizomatous. Leaf mucilage glands and gynophore hair apices provide useful new taxonomic characters. The three interspecific hybrids synthesized in the field in California are intermediate between their parents and similar to numer- ous putative hybrids. Typha angustifolia X latifolia (T. X glauca Godron), widespread in temperate zones, and T. domingensis X latifolia, known from California and southern Europe, are morphologically similar and mostly sterile. Typha angustifolia X domingensis, known as hybrid swarms in California and reportedly southern France, is mostly fertile. Trihybrid populations occur in California and probably in the Southeast. The three species and three hybrids are diploids (n = 15). Microsporogenesis is regular in the three species and in T. angustifolia X domingensis with 15 bivalents at MI. About 1 to 6 univalents per PMC, infrequent bridges and rare micronuclei occur in both T. angustifolia X latifolia and T. domingensis X latifolia. The species remain distinct due to either hybrid sterility or relatively narrow zones of sympatry. Hybridization and introgression have probably allowed the evolution of ecotypic races. The hybrids appear to be better adapted than the parents to habitats with rapidly fluctuating water level.