Floral structure and development and systematic aspects of some 'lower' Asparagales

Abstract

Floral structure and development of representatives of Asteliaceae, Blandfordiaceae, Boryaceae, Doryanthaceae, and Hypoxidaceae, all members of the `lower' Asparagales, were studied comparatively. The results are discussed in the light of new molecular systematic studies, but also with regard to established morphological characters in related groups. Stamen shape varies considerably within and between taxa: the shape of anthers is from X-shaped, sagittate to non-sagittate, they are either latrorse or introrse, basifixed, centrifixed or dorsifixed. Gynoecia are syncarpous up to the stigmatic region in all taxa. Ovaries of Doryanthaceae and Hypoxidaceae are inferior, but they are superior in Asteliaceae, Blandfordiaceae and Boryaceae. All ovaries have at least a short synascidiate zone. With the exception of Astelia alpina (Asteliaceae), the ovaries are trilocular. Ovaries of Asteliaceae contain mucilage, which is secreted from trichomes on the funicle and on the placenta. Although flowers are polysymmetric at anthesis, they are monosymmetric in earliest stages with a developmental gradient from adaxial to abaxial. Perianth organs arise individually from either a concave (taxa with inferior ovary) or convex (taxa with superior ovary) apex. Hypoxidaceae have pollen flowers with free stamens. One species, Curculigo capitulata, has Solanum-type flowers with postgenitally united stamens. It is most probably pollinated by buzzing bees. All other taxa have nectariferous flowers with internal or external septal nectaries.