GONZALEZ Ana Maria
Anatomía y Vascularización floral de Piriqueta racemosa, Turnera hassleriana y Turnera joelii".
GONZALEZ, ANA MARIA
Ed. Instituto de Botánica del Nordeste.
Lugar: Corrientes; Año: 1993 vol. 7 p. 143 - 184
Anatomía y Vascularización Floral de Piriqueta racemosa, Turnera hassleriana y Turnera joelii (Turneraceae) Ana Maria Gonzalez The floral vascular anatomy of three species belonging to two genera of Turneraceae is analyzed. The indumentum and the anatomical structure of peduncle, prophyls, perianth, nectaries, crown, androecium and gynoecium are described as well. The ovary is surrounded by a tube, the appendicular nature of which is confirmed: its basal portion is composed of calyx, corolla and staminal filaments, and its distal portion is formed only by the perianth. The expression "floral tube" is used to name this structure, following Takhtajan (1991). The nectaries are placed between the perianth and the stamens; in Piriqueta they are adnated to the floral tube while in Turnera they are located on the stamens. T. joelii seems to be more advanced because of the development of a nectar pocket. The crown is present only in Piriqueta, it has papillose epidermal ceils and no vascular supply. Each episepalous stamen is supplied by one amphicribal bundle, which ends in the connective tissue. The wall of the mature anther is composed of epidermis and endothecium. Pollen grains are tricolporate and reticulate.The gynoecium has transmission tissue on the apical inner surface of the ovary (compitum), covering the placentae, ascending within the styles and appearing on the stigmas. The ovules are anatropous, bitegmic, crassinucelate, with zigzag micropyle. The vascular pattern is similar in the three species analyzed: ten compound traces diverge from the stele in the bottom of the receptacle; five of them are petal traces, which in the apex of the floral tube will originate the lateral sepal bundles and the petal bundles. 11w remaining five traces split to provide the central sepal trace and the staminal trace. Then two rows of three traces are borne, the dorsal and marginal carpel traces; in T. joelii some of these depart from the compound sepal-stamen traces. In T. hassleriana the traces of placentas are basally fused with the marginal carpel traces while in P. racemosa and T. joelii they are free. The ovules bundies are home on the placental bundies. The dorsal carpel bundies ascend along the styles, and then divide to enter in the bottom of the stigma branches. The marginal carpel bundies end in the apex of the ovary. P.racemosa and T. hassleriana have superior ovary, while T. joelii has superior and half inferior ovaries. In the last case the receptacle is slightly cup-shaped. The lengthy adnation of calyx and corolla, the presence of nectar pockets, the nascent half inferior ovaries, and the fusion of some carpel bundles with the common bundles for sepal and stamen confirm the advanced evolutionary position of the series Canaligerae.T. hassleriana bas some characters as the peduncle vascular supply in the shape of an ectophloic siphonostele and very brief sepal-stamen common bundies that seen to be less advanced.