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

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.

Morphological and anatomical development in the Vitaceae. IV. Floral development in Parthenocissus inserta

The floral ontogeny of Parthenocissus inserta, based on histological and three-dimensional observations, is presented. The inflorescence primordium arises in a leaf-opposed position at two of three nodes. It becomes subtended by a bract, and then bifurcates equally to form a lateral and a main arm. Inflorescence branches are initiated on both arms to form a series of dichasia. The transition from inflorescence branch primordium to floral primordium is marked by the initiation of three sepal primordia. Subsequently a ring primordium forms as the fourth and fifth sepal primordia are initiated, resulting in a calyx which encircles the floral apex. Petals and stamens arise simultaneously as five common petal–stamen primordia, alternating with the sepals. They bifurcate to form separate petal and stamen primordia. The petals are greenish, valvate, hooded, and are separate at maturity. The tetrasporangiate anthers are introrse and pollen is tricolporate. The gynoecium arises as a ring primordium. Two septa arise from the inner gynoecial wall and the floral apex, and will eventually form an essentially two-loculed superior ovary. Two ovules are initiated from the base of each septum. Each of the four ovules is anatropous and bitegmic at maturity. A disc arises from the base of the gynoecium. It appears as five pinkish protuberances of the ovary base at maturity and secretes a nectarlike substance. The fruit is a one- to four-seeded blue-black berry.

Studies in the Alismataceae. IV. Developmental morphology of Ranalisma humile and comparisons with two members of the Butomaceae, Hydrocleis nymphoides and Butomus umbellatus

The development of the foliage leaf bearing axes in Ranalisma humile (Kunth.) Hutch. and Hydrocleis nymphoides Buch. is similar in that both show sympodial development, each branch of the sympodium terminating in an inflorescence; in Butomus umbellatus L. the inflorescence is lateral and the vegetative axis is monopodial.Inflorescences of Ranalisma can adopt a horizontally growing pseudostolon form in which floral meristems are formed but abort at an early stage; there is no basic difference between the organ complements of the pseudostolon and the erect inflorescence.Inflorescences of Hydrocleis and Ranalisma have similar developmental patterns. In both, the main axis terminates in a floral primordium while a large bud is developed in the axil of the first of two bracts below the flower. The lateral bud in Hydrocleis develops into a sympodial bud complex consisting of flowers, a vegetative bud, and an inflorescence branch which repeats the pattern of development; in Ranalisma the lateral bud gives rise only to a vegetative bud and an inflorescence branch. Ranalisma appears to possess a reduced form of the kind of inflorescence development found in Hydrocleis.The inflorescence of Butomus also terminates in a flower. It has three bracts, each subtending a set of multiple axillary buds. Each individual bud develops into a sympodially arranged set of flowers.Previously proposed isolation of Butomus from other Butomaceae and Alismataceae is further emphasized by developmental data. Ranalisma provides a connecting link between Alismataceae and the Butomaceae excluding Butomus (i.e. the Limnocharitaceae of some authors).