Evolution of the Anther Gland in Early-Branching Papilionoids (ADA Clade, Papilionoideae, Leguminosae).

Papilionoideae is the most diverse subfamily of Leguminosae, especially in terms of floral morphology. The ADA clade shows some exciting floral features among papilionoids, such as anther glands. However, the evolution of the anther glands in such early-branching papilionoids remains unknown. Thus, we compared the occurrence, distribution, morphology, and evolutionary history of the anther glands in species of the ADA clade. Floral buds and/or flowers in 50 species were collected from herbarium specimens and investigated using scanning electron and light microscopy and reconstruction of ancestral character states. The anther apex has a secretory cavity, secretory duct, and phenolic idioblast. The lumen shape of the cavity and duct is closely related to the shape of the anther apex. The oval lumen is located between two thecae, the spherical lumen in the prominent anther apex and the elongated lumen in anthers with a long apex. The occurrence of cavities/ducts in the anther in only two phylogenetically closely related subclades is a unifying character -state. The floral architecture is not correlated with cavity/ducts in the anther but is possibly related to the type of pollinator. Future research needs to combine floral morphology and pollination systems to understand the evolution of floral designs and their diversification.

Resolving the non-papilionaceous flower of Camoensia scandens, a papilionoid legume of the core genistoid clade: development, glands and insights into the pollination and systematics of the group.

Camoensia scandens is a papilionoid legume inserted in the core genistoid clade. It has large, crepuscular, scented flowers but the corolla is non-papilionaceous, which deviates from the pattern found in the subfamily. The vexillum has a folded claw, forming a tube, which is opposed to the androecium opening; all petals have yellow-gold crinkled margins. In addition, there is a long hypanthium, which stores a translucid liquid. The goal of this study is to elucidate the ontogenetic pathways that result in such a peculiar flower and the glands responsible for the sweet fragrance of the petals. Floral buds and flowers were processed for SEM, TEM and light microscopy analyses. Five sepals arise unidirectionally followed by five petals that initiate simultaneously. After the petals, 11 stamens emerge unidirectionally; a pair of adaxial stamens is opposite to the vexillum. In the intermediate developmental stages the sepals unite basally; the two adaxial sepals unite with each other to a greater extent than with the other sepals. The filaments are basally connate, forming a tube with an adaxial opening at the base. The carpel emerges concomitantly with the two abaxial antepetalous stamens. The long hypanthium forms from the outer floral organs (base of the sepals, petals, filaments) and is attached to the base of the stipe. The corolla is noticeable in the intermediate stages of development. The crinkled golden margins house scent glands formed of a secretory epidermis with secretory trichomes and secretory subepidermal cells. The odor is composed of neutral polysaccharides, nitrogenous substances and essential oils. An extensive nectariferous region is found on the inner surface of the hypanthial tube. The nectar is translucent, viscous and released through large pores. The comparison of our data with that of other genistoid flowers enabled discussions about the pollination and systematics of the group.

Comparative development of rare cases of a polycarpellate gynoecium in an otherwise monocarpellate family, Leguminosae.

PREMISE OF THE STUDY: Apocarpy (i.e., free carpels) is considered to be the basal condition for ovary development in angiosperms. Yet it only occurs in 10% of angiosperm species, of which another 10% are monocarpellate. Most legume flowers are monocarpellate. Species with polycarpellate gynoecia occur in about 15 genera with most representatives in Mimosoideae. In the present study, we analyze legumes with polycarpellate flowers with the aim of improving our understanding of gynoecium evolution. METHODS: Flowers of nine legume species from five genera were analyzed using a scanning electron microscope (SEM). KEY RESULTS: In Leguminosae, carpels usually form as individual primordia or protuberances. Inga congesta differs slightly from this pattern in that the central apex bulges outward before the formation of individual carpel primordia. While legumes usually develop entirely plicate carpels, flowers of Acacia celastrifolia and Inga bella show an intermediate type of carpel morphology with a distal plicate zone and a small proximal ascidiate zone. Carpels in Inga congesta and Archidendron glabrum are sometimes slightly fused at the ovary base. The orientation of carpel clefts seems to reflect the floral symmetry. They are directed to the floral center in mimosoids and caesalpinioids, whereas in Swartzia dipetala carpel clefts are oriented to the adaxial side. CONCLUSIONS: Polycarpelly arose at least seven times independently in Leguminosae. The polycarpellate condition appears to be correlated with polyandry, and in most instances, it is accompanied by a profound change in floral organization from a closed to an open system.