Calcium oxalate crystals in tribe Galegeae (Leguminosae) including foliar crystal macropattern development in Caragana frutex

摘要

Galegeae was reported in 1987 to be unique among papilionoid tribes because calcium oxalate crystals were shown to be mostly lacking. We surveyed leaves of 45 species from 20 genera, mostly from herbarium specimens. A living species (Caragana frutex (L.) K. Koch) with crystals was also studied developmentally, important because only three other species have been similarly studied. Herbarium specimens and various stages of C. frutex leaflets were bleached, dehydrated, cleared in alcohol-xylol, and made permanent. Freehand sections of C. frutex were mounted in glycerine. Crystals were detected microscopically and are generally lacking among Galegeae genera. This supports tentative contemporary opinion that the tribe is unnatural. Crystals provide new,potentially useful systematic data. Variously differing unicellular trichomes were also described in the survey. Caragana frutex leaflets have a previously undescribed macro-pattern development: crystals form only along veins, except for late-season prisms in scattered palisade parenchyma. Crystals form progressively base to apex, first following along successive major veins from midvein to margin and then in later-developing smaller veins, progressing acropetally. The midvein remains almost crystal-free until leaflets are at or near full size. Crystal macropattern development in C. frutex leaflets suggests that crystallization may be influenced by the whole organ, as well as by individual cells.