Micromorphological structure of the fruit and seed of Smodingium argutum (Anacardiaceae), as an adaptation to its natural habitat

Smodingium argutum E. Mey. ex Sond, is very closely allied lo the genus Rhus L., but easily distinguished from it by the inflorescence which is a thyrse, ils pendulous ovule; an ‘apical-lateral’ style; winged fruit; a sap (noxious secretion from all organs) which turns black on exposure to air; indumentum on the pedicel, bracteoles and calyx, as well as an unique, papery pericarp. The latter comprises a uniseriate exocarp a mesocarp with large secretory ducts and a mostly two-layered, weakly developed endocarp. An anatropous, bitegmic, crassinucellate ovule develops into a small, partially pachychalazal, exalbuminous seed, also characterized by an endotegmen and lipidie nutrient reserves. The following characters are obviously of crucial importance for the survival of this species, efficient fruit dispersal, aided by the samaroid drupe; easy germination; the well-developed cuticles on the calyx, ovary wall and exocarp; and the thick cuticular layer delimiting the mature integumentary seed coat, which, together with cell wall impregnations in the physiologically mature hypostase cells, protects the embryo against dehydration