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Notes on the Flora of Mexico: World Distribution of the Woody Dicotyledonous Families and the Origin of the Modern Vegetation

A. J. Sharp
Journal of Ecology
Vol. 41, No. 2 (Aug., 1953), pp. 374-380
DOI: 10.2307/2257048
Stable URL: http://www.jstor.org/stable/2257048
Page Count: 7
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Notes on the Flora of Mexico: World Distribution of the Woody Dicotyledonous Families and the Origin of the Modern Vegetation
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Abstract

The flora of Mexico includes 143 dicotyledonous families with woody species. These may be classified on the basis of their distribution outside Mexico into the following categories which are listed according to the number of families in each: 1. Tropical (Araliaceae, Bixaceae, Bombacaceae, Caesalpiniaceae, Chloranthaceae, Cochlospermaceae, Combretaceae, Connaraceae, Cunoniaceae, Dilleniaceae, Elaeocarpaceae, Flacourtiaceae, Hernandiaceae, Hippocrateaceae, Krameriaceae, Loranthaceae, Moraceae, Myristicacaeae, Myrsinaceae, Myrtaceae, Ochnaceae, Opiliaceae, Piperaceae, Rubiaceae, Sabiaceae, Sapindaceae, Simaroubaceae and Surianaceae) . . . . . . . . . . . 28 2. Tropical and Subtropical (Acanthaceae, Annonaceae, Apocynaceae, Bignoniaceae, Buxaceae, Capparidaceae, Convolvulaceae, Crassulaceae, Diospyraceae, Erythroxylaceae, Gesneriaceae, Icacinaceae, Lauraceae, Loganiaceae, Meliaceae, Menispermaceae, Mimosaceae, Olacaceae, Oxalidaceae, Rhizophoraceae, Sapotaceae, Solanaceae, Sterculiaceae, Verbenaceae, Vitaceae and Zygophyllaceae) . . . 26 3. Temperate, mostly Northern Hemisphere (Aceraceae, Aesculaceae, Amygdalaceae, Berberidaceae, Betulaceae, Cistaceae, Ericaceae, Fagaceae, Grossulariaceae, Juglandaceae, Malaceae, Nyssaceae, Papaveraceae, Platanaceae, Staphyleaceae, Styracaceae and Ulmaceae) . . . . . . . . . 17 4. Mainly American with a small number of Species elsewhere (Batidaceae, Burseraceae, Cactaceae, Escallionaceae, Hydrophyllaceae, Loasaceae, Malpighiaceae, Melastomaceae, Passifloraceae, Polemoniaceae, Theophrastaceae, Turneraceae and Vochysiaceae) . . . . . . . . . . . . 13 5. Generally distributed but more in tropics (Anacardiaceae, Asclepiadaceae, Celastraceae, Euphorbiaceae, Hypericaceae, Lobeliaceae, Lythraceae, Malvaceae, Phytolacaceae, Rutaceae, Tiliaceae and Urticaceae) . . . . . . 12 6. Cosmopolitan except for coldest regions (Amaranthaceae, Aquifoliaceae, Aristolochiaceae, Boraginaceae, Nyctaginaceae, Oleaceae, Portulacaceae, Plumbaginaceae, Rhamnaceae and Violaceae) . . . . . . . . . 10 7. Endemic to the warmer areas of the Americas (Brunelliaceae, Caricaceae, Cyrillaceae, Julianaceae, Lacistemonaceae, Marcgraviaceae) . . . . . 6 8. Cosmopolitan (Asteraceae, Chenopodiaceae, Fabaceae, Menthaceae, Rosaceae and Scrophulariaceae) . . . . . . . . . . . . 6 9. Mainly north temperate but some extending into southern hemisphere (Cornaceae, Hamamelidaceae, Hydrangeaceae, Myricaceae, Salicaceae) . . . 5 10. Generally distributed but more in temperate areas (Caprifoliaceae, Onagraceae, Polygalaceae, Polygonaceae and Ranunculaceae) . . . . 5 11. Almost endemic to Mexico (Crossosomataceae, Fouquieriaceae, Koeberlinaceae, Pterostemonaceae) . . . . . . . . . . . 4 12. Mainly southern hemisphere (Monimiaceae, Proteaceae and Thymeleaceae) 3 13. Not readily classified (Clethraceae, Coriariaceae, Frankeniaceae Goodeniaceae, Magnoliaceae, Symplocaceae, Theaceae and Winteraceae) . . . . 8 Although about three-fourths of Mexico has temperate vegetation, the tropical areas have a richer flora with many more families, genera and species. A review of the historical geology of Mexico suggests that after the development of the Angiosperms, but prior to the Pliocene, there was little continuous area with sufficient elevation to support a temperate vegetation all through that time. The present temperate element in the flora of Mexico must have come from the north during late Pliocene and the Pleistocene. Rich tropical vegetation could have covered such areas of Mexico as were exposed from early Mesozoic to the Pliocene. The tropical vegetation of the lowlands to-day may have elements which originated in Mexico and other elements which came from the north prior to the Pliocene, and still other elements which came and are coming from the south.

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