LEAF MORPHOLOGY OF CALANDRINIA AND MONTIOPSIS (PORTULACACEAE)

Calandrinia sect. Calandrinia, C. sect. Monocosmia, and some species of C sect. Acaules share identical leaf blade and petiolar morphology, fimbrial veins, predominantly brachytetracytic and staurocytic stomata surrounded by a cycle of subsidiary-like cells, and unicellular ribbed trichomes or papillar trichomes. Other species of C. sect. Acaules have irregularly brochidodromous venation without a fimbrial vein, predominantly brachyparacytic stomata, and/or no trichomes; venation and stomatal morphology in these species is similar to that found in Montiopsis. Leaves of Montiopsis lack petioles, have glandular or eglandular, uniseriate- and/or multiseriate-multicellular trichomes (although some examined specimens of M. subg. Dianthoideae appear to be glabrous), and generally have brachyparacytic stomata (although some examined specimens of subgenus Dianthoideae have a small proportion of brachytetracytic/staurocytic stomata with an outer cycle of cells). Leaves of M. subg. Montiopsis also have barbellate trichomes apparently composed of elongate hair cells, and have predominantly brachyparacytic or anomocytic stomata. Phylogenetic analysis of foliar characters of Portulacaceae: (1) supports a close relationship between C sects. Calandrinia and Monocosmia and species of C. sect. Acaules; (2) indicates that C. sect. Acaules may be paraphyletic with respect to the preceding taxa; (3) provides weak evidence contradicted by nonfoliar evidence that Claytonia and Montia may be nested within Calandrinia; (4) provides weak evidence linking Montiopsis with Calandrinia; and (5) indicates that foliar characters may not be more homoplasious than nonfoliar. Phylogenetically analyzed systematic accounts of foliar morphology, such as that presented here, may provide a basis for advancing theories on the relationship between leaf form, function, and ontogeny.