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Accueil du site → Doctorat → États-Unis → 1981 → A TAXONOMIC STUDY OF THE NORTH AMERICAN SPECIES OF LYCIUM (SOLANACEAE)

University of Texas at Austin (1981)

A TAXONOMIC STUDY OF THE NORTH AMERICAN SPECIES OF LYCIUM (SOLANACEAE)

CHIANG-CABRERA, FERNANDO

Titre : A TAXONOMIC STUDY OF THE NORTH AMERICAN SPECIES OF LYCIUM (SOLANACEAE)

Auteur : CHIANG-CABRERA, FERNANDO

Université de soutenance : University of Texas at Austin

Grade : Doctor of Philosophy (PhD) 1981

Résumé
The genus Lycium (Solanaceae) comprises about 100 species of mostly woody, thorny perennials, distributed among three sections. The taxa occur in the arid and semiarid parts of the world, though a few species are found in more mesic habitats. Synopses of the taxonomic history of the genus and its ethnobotany are given. Pollen studies show the pollen grains to be medium-sized (25-49 um), prolate, tricolporate, with striate to reticulate-striate exine sculpturing, except those of Lycium shockleyi, which show echinate sculpturing. Paper-chromatography based on the flavonoid compounds of the leaves proved useful, in conjunction with morphic information, in solving some taxonomic problems. Chromosomal counts were made for several of the taxa, the most common chromosome number being n = 12 ; Lycium californicum var. californicum showed n = 24 ; Lycium fremontii var. fremontii showed n = 48 and one count of n = 60. Counts of n = 18, previously reported in the literature, were not encountered. In this treatment, twenty-one North American species are recognized and divided into two sections, Lycium and Sclerocarpellum C. L. Hitchc. Four species previously placed in the former section are transferred to the latter. A third, exclusively South American, section, Schistocalyx Dunal, is reinstated and typified, and that name is to be used instead of Selidophora C. L. Hitchc. A taxonomic treatment is presented, based on morphology of herbarium specimens and observations made in the field. The most useful morphic characters are shape and relative length of the calyx-tube, the calyx-lobes and the corolla-lobes ; pubescence of calyx and corolla, pubescence of corolla-lobes, point of insertion of the filaments, relative length of the stamens, type and shape of fruit, and shape and pubescence of leaves. Keys, nomenclature and descriptions are provided.

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