Floral Anatomy in the Saxifragaceae Sensu Lato. Ii. Saxifragoideae and Iteoideae

Abstract

The floral anatomy and morphology of 26 species from the Saxifragoideae and three from the Iteoideae are described and compared. The flowers of the Saxifragoideae are predominantly actinomorphic, partially epigynous and/or perigynous, and pentamerous, with two carpels which bear numerous ovules. There is usually some degree of independence between carpels, and the normally separate styles possess both a canal and transmitting tissue. Generally, staminodia are absent and nectariferous tissue, which is not vascularized, is present. The subfamily is characterized by large multicellular trichomes with globular, often glandular, heads. Placentation may be parietal, axile, or transitional between the two; parietal appears to be a derived condition in the subfamily. The vascular cylinder in the pedicel generally consists of several to many discrete bundles from which diverge ten compound traces at the base of the receptacle, leaving an inner cylinder of vascular strands that coalesce at a higher level into either as many ventral bundles as carpels or twice that number. In the former case, each ventral bundle consists of one‐half of the vascular supply to each adjacent carpel and separates into individual ventral strands in the distal half of the ovary. The ventral bundles provide vascular traces to the ovules and, along with the dorsals, extend up the style to the stigma. Each trace diverging in a sepal plane typically supplies one or more carpel‐wall bundles, a median sepal bundle, and a stamen bundle. Each petal‐plane trace usually provides one or more carpel‐wall bundles, a lateral trace to each adjacent sepal, a petal bundle and, in flowers with ten stamens, a stamen bundle. Dorsal carpel bundles are usually recognizable and may originate from traces in either perianth plane. While the position of Ribes remains problematical, its floral structure does not easily exclude it from the Saxifragoideae. Floral structure in the Iteoideae is remarkably similar to that in the Saxifragoideae, the main differences being a lesser degree of independence between carpels, generally narrower placentae with somewhat fewer ovules, and the presence of only unicellular, acutely pointed epidermal hairs as opposed to the relatively complex, multicellular trichomes prevalent in the Saxifragoideae.

The floral development and floral anatomy ofChrysosplenium alternifolium, an unusal member of the Saxifragaceae

“…35). A similar observation was made for Chrysosplenium americanum by Bensel and Palser (1975). Leaves were found to be simple with one layer of palissade cells and anomocytic stomata on both surfaces.…”

“…This should be studied in other species as suggested by Bensel and Palser (1975). The concrescence of the ovary with the receptacle is complete in several species of Chrysosplenium, viz.…”

“…Klopfer 1973, Roels et al 1997, Vandeputte 1993). Bensel and Palser (1975) report some Heuchera sp. with very small petals, and in Tolmiea and Bensoniella petals are minute or absent (Engler 1930, Klopfer 1973.…”

“…Most authors do not distinguish between multicellular glandular hairs and colleters in the Saxifragaceae (e.g. Bensel and Palser 1975, Engler 1930: "mehrzellige DrSsen", Gornall 1986). This distinction should be emphasized as colleters differ from ordinary multicellular trichomes in having a specific position and function (protecting the developing meristem by producing a viscous secretion), and may have systematic value.…”

The questionable relationship of Montinia (Montiniaceae): evidence from a floral ontogenetic and anatomical study

“…Our information is based on Polyosma and Escallonia. Some anatomical similarities with Montinia exist within the core Saxifragaceae (Bensel and Palser, 1975a) in the presence of compound ventral bundles, separated from the peripheral bundles in the base of the flower, and the arrangement of peripheral bundles in the ovary wall. e all Solanaceae are hypogynous, except for Nothocestrum latifolium, which is perigynous (Armstrong, 1986).…”