Cuticle micromorphology of leaves of Pinus (Pinaceae) from Mexico and Central America

Cuticle micromorphology of 34 taxa of Pinus from Mexico and Central America was studied with scanning electron microscopy, and leaf morphology was des cribed. In total, 29 characters, 22 from the inner cuticular surfaces and s even from the outer, were described in detail. These characters have value either for testing infrageneric classifications or for identifying individu al taxa. Characters relating to the periclinal wall texture of the epiderma l cells, the shape and degree of development of the anticlinal walls of the epidermal cells, the basal and apical shapes of anticlinal epidermal cell walls, the continuity of the epidermal cells, the size ratio of the polar t o lateral subsidiary cells, the grooves on subsidiary cells, the cuticular flanges between guard and subsidiary cells, the groove near the bristles an d the elevation of the Florin ring ridge and striations on the Florin ring are particularly useful for infrageneric classification. The agreement betw een these characters and infrageneric classifications is discussed. Charact ers relating to the end wall shapes of the epidermal cells, the relative le ngth of epidermal cells, the shape of the stomatal apparatus, the texture o f guard and lateral subsidiary cell surfaces, the polar extensions, the num ber of subsidiary cells and epidermal cell layers between stomatal rows, th e integrity of stomatal rows, cell numbers between stomata in a row, cuticu lar flanges between guard cells, bristle flanges and surface textures, epic uticular waxes, striations on Florin rings and stomatal shapes, contain som e important information for identifying Mexican pines. The distribution of the states of each character is compared with that of the Asian pines. Cuti cular characters are used to help determine the affinities of taxonomically difficult taxa. (C) 2001 The Linnean Society of London.