Morphological and anatomical development in the Vitaceae. VI. Cissus antarctica

• Published in: Canadian Journal of Botany
• Main Authors: Gerrath, Jean M., Posluszny, Usher
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1994
• Subjects: Plant Science; Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1139/b94-084; http://www.nrcresearchpress.com/doi/pdf/10.1139/b94-084

The developmental morphology of Cissus antarctica Vent, was followed from seed to seed. As in the other taxa in the family we have examined (Vitis, Parthenocissus, Ampelopsis), both leaves and uncommitted primordia arise on the flank of the apical meristem. Also as in the other taxa, the uncommitted primordium may develop into either a tendril, an inflorescence, or an intermediate organ. An abaxial bract forms on the uncommitted primordium. If the primordium is going to develop into an inflorescence, the lateral arm develops in the axil of the bract. A second order inflorescence arm may also form and it is on these two axillary structures that most of the flowers develop. Each arm of the inflorescence forms a compound series of dichasia, with each dichasium oriented at 90° from the previous one. Flowers are tetramerous. The first two sepals are initiated at approximately 90° to the last-formed inflorescence branch primordium, in the same position as the dichasial bracts would form. Thus the early distinction between a floral and an inflorescence branch primordium is very difficult. A ring primordium then forms and the calyx becomes continuous. The petals arise simultaneously, followed by the stamens, which are petal-opposed. Thus there is no common petal–stamen primordium. The gynoecium arises as a ring primordium, and subsequently two septa form opposite one another on its inner wall. The septa touch, but they do not fuse. Two ovules form at the base of each septum. A floral nectary develops from the ovary base. At anthesis, the greenish petals reflex, usually for a day or less and then are shed, along with the stamens. Fruits are dark bluish and are usually one-seeded. Key words: development, flowers, Vitaceae, Cissus, morphology.