Comparative leaf anatomy of Salix species and hybrids

Abstract

Epidermal features, mesophyll differentiation and calcium oxalate characteristics of 19 species and 12 hybrids of Salix are described. The species and hybrids can be distinguished by the presence or absence of the following epidermal features: striated cuticle; stomata; covering trichomes; beaded anticlinal walls, and diosmin-like njstals. In or near marginal teeth, glandular trichomes are present in all cases. The leaf veins of all specimens examined have calcium oxalate prism sheaths and, with the exception of S. herbacea, cluster crystals in some cells of the mesophyll. Most sprcies studied in the subgenus Salix show: both adaxial and abaxial stomata; striated cuticle metopllyll of palisade cells, with little or no spongy mesophyll, but with a well-defined hypodermis, and absence of thick-walled, sinuous trichomes. Characteristic features of the subgenus Caprisalix are: abaxial stomata only; epidermal crystals; smooth cuticle; mesophyll diflerentiated into palisade cells and spongy mesophyll and without a hypodermis, and trichomes more numerous and varied than those of the subgenus Salix. Leaves of the two species of the subgenus Chaemelia examined and those of S. lapponum, have predominantly anomocytic stomata, whereas all the other leaves studied have predominantly paracytic stomata. The anatomical features described, in conjunction with the morphologiral characters, enable the species and hybrids of Salix studied to be autheenticated.