Comparative floral anatomy of Pontederiaceae

Floral anatomy is described in eight species (representing five genera) of Pontederiaceae, and floral ontogeny is described in Pontederia cordata. The results are assessed in the context of recent phylogenetic work on Pontederiaceae, which indicates that the unilocular ovary condition has been achieved by two different, non-homologous routes in Pontederiaceae: via loss of interlocular septa in Heteranthera and Hydrothrix , and via pseudomonomery in Pontederia , which has a single fertile carpel. Absence of septal nectaries has evolved more than once in Pontederiaceae, at least in Heterantha and Monochoria , probably due to a transfer of the insect reward from nectar to pollen in these taxa. The presence of an elliptical or linear unvascularized appendage on the abaxial outer stamen in Monochoria is also probably correlated with enantiostyly. In Pontederia , air spaces in the ovary wall are modified into canals, each with a ring of apparently secretory epithelial cells.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 395–408.     

Calcium Oxalate Crystals in Monocotyledons: A Review of their Structure and Systematics

Three main types of calcium oxalate crystal occur in monocotyledons:raphides, styloids and druses, although intermediates are sometimesrecorded. The presence or absence of the different crystal typesmay represent ‘useful’ taxonomic characters. Forinstance, styloids are characteristic of some families of Asparagales,notably Iridaceae, where raphides are entirely absent. The presenceof styloids is therefore a synapomorphy for some families (e.g.Iridaceae) or groups of families (e.g. Philydraceae, Pontederiaceaeand Haemodoraceae). This paper reviews and presents new dataon the occurrence of these crystal types, with respect to currentsystematic investigations on the monocotyledons. Copyright 1999Annals of Botany Company Calcium oxalate, crystals, raphides, styloids, druses, monocotyledons, systematics, development.     

Structure and development of the stigma, style and ovary of Caesalpinia pulcherrima (L.) Sw., post-anthesis, pre- and post-pollination

The stigma of Caesalpinia pulcherrima is crateriform. The crater continues as a slit-like canal through the style and into the ovary. Both crater and canal are lined by several layers of fusiform and thin-walled cells which are continuous in two narrow regions in the ovary. Postanthesis and before pollination, the middle lamella of cells lining the stigmatic crater and stylar transmitting tissue undergoes dissolution. This occurs in a progression down the style with cells separating partially or wholly from neighbours. Dissolution is initiated at intercellular junctions where wall fibrils loosen and variously-sized and -shaped holes appear. Cytoplasmic changes include increased dictyosome activity, increased rough and smooth endoplasmic reticulum at the periphery of cells and accumulation of electron opaque deposits at the plasma membrane. The crater fills with stigmatic fluid and the diameter of the stylar canal increases. Pollen germinates in the secretion-filled crater, and pollen tubes grow down the style between the cells of the transmitting tissue but do not enter the canal. They emerge at the entrance to the ovary cavity and grow over one or two narrow strips of ovarian transmitting tissue cells which are present throughout the length of the ovary close to the ovules. This ensures that tubes grow in close proximity to the micropyles.