A fossilized aroid infructescence, Albertarum pueri gen.nov. et sp.nov., of Late Cretaceous (Late Campanian) age from the Horseshoe Canyon Formation of southern Alberta, Canada

A fossilized aroid infructescence has been recovered from the Horseshoe Canyon Formation in southern Alberta, Canada. Its stratigraphic position places it near the end of the Campanian Stage of the Late Cretaceous Epoch, at an absolute age of approximately 72 million years before present. It is one of the few Cretaceous aroid fossils known at present, and it represents a new genus of Araceae, here named Albertarum. The infructescence is fertile to the apex, and the flowers must have been bisexual. Flowers bear remains of a long, attenuated style, surrounded by a perigone of six tepals. A fracture reveals ellipsoid seeds with a thick, ribbed testa and traces of a raphe, arranged in groups of three. The gynoecium was probably trilocular with one ovule per locule, and ovules were anatropous, probably with apical–parietal or axile placentation. Bisexual, perigoniate flowers occur in subfamilies Gymnostachydoideae, Orontioideae, Pothoideae, Monsteroideae, and Lasioideae, no genera of which have ribbed seeds, but the infructescence and stylar region of Albertarum resemble those of extant Symplocarpus (Orontioideae). The Horseshoe Canyon Formation was deposited in a delta plain setting, and like Symplocarpus, Albertarum probably grew in a wetland environment.Key words: fossil, Araceae, Symplocarpus, Albertarum, Limnobiophyllum, Mayoa.

Floral development and anatomy of Pentadiplandra (Pentadiplandraceae): a key genus in the identification of floral morphological trends in the core Brassicales

The development and anatomy of leaves and flowers have been investigated in the monotypic species Pentadiplandra brazzeana to discuss its position relative to the core Brassicales and to clarify floral evolutionary trends within the order. Young leaves are flanked by two large stipules that shrivel at anthesis. Young flowers develop as elliptical primordia on a flattened raceme. Sepal initiation is sequential, starting with the lateral sepals and ending with three median sepals. The petals and diplostemonous androecium arise as regular whorls. Five antesepalous carpels develop into a saccate gynoecium with axile placentation. Petals develop a cushion-like basal appendage covering the extrastaminal nectary. Several ontogenetic and anatomical data of the flower support the basal position of Pentadiplandra in the evolution of the core Brassicales and for the derivation of the order from pentamerous diplostemonous ancestors. A derivation of the tetramerous Capparaceae and Brassicaceae as well as hexamerous Tovariaceae is discussed. A number of synapomorphies are identified: sequential sepal initiation with laterals preceding median sepals, retarded petal growth, a (andro)gynophore, the extrastaminal nectary, and stipulate leaves. The peculiar androecium of the Brassicaceae is caused by the strong median compression of the flower, leading to the loss and displacement of median stamens. The derivation of a parietal placenta from an axile placenta is supported. Evidence supports a close link with either Tovariaceae or Capparaceae, concomitant with macromolecular results.Key words: core Brassicales, Capparaceae, Pentadiplandra brazzeana, Tovariaceae, molecular phylogeny, floral development, anatomy, diplostemony, placentation.

Vascularisation de la fleur de Spathiphyllum wallisii

The hermaphrodite flowers of Spathiphyllum wallisii have six tepals and six extrorse stamens. Gynoecia are either tri- or quadri-locular. In trilocular gynoecia, three dorsal bundles and three complex ventral bundles, each corresponding to the union of two simple ventral bundles belonging to adjacent carpels, are found in the ovarian wall. In the central axis of the ovary, three placental bundles rise to the level of ovular attachment. Each of these splits into two ovular traces. There are two ovules in each locule. When the gynoecium is quadrilocular, four placental bundles, four dorsal bundles, and four complex ventral bundles are usually present. In the flowers of Spathiphyllum wallisii, each carpel is vascularized by a dorsal bundle and by two simple ventral bundles. The path of the placental bundles is typical of that of Araceae with axile placentation.

Vascularisation de la fleur de Calla palustris (Araceae)

Based on floral vascular system, the authors analysed the problem of pseudomonomeria, and the inter-generic relationships within the Calloideae. The hermaphrodite flowers of Calla do not have a perianth. The superior, unilocular ovary is surrounded by 10 to 12 extrorse stamens. Most of these flowers have an ovary wall which receives three carpellary traces. These three traces divides again to produce 9–12 bundles. At the base of the ovules, an oval vascular plexus can be seen on which the traces of the ovules are inserted. It originates from three carpellary bundles, even though it is connected to certain staminal traces. The anatomical study showed that the syncarpous gynoecium of Calla is composed of three carpels that are joined edge to edge. The bitegmic, anatropous, apotropous ascending ovules are located on a basal placenta. The number of ovules varies from 4 to 10. The basal placentation of Calla is of the basal-axile type. It derives from an axile placentation which is similar to that found in Lysichitum. Among the Calloideae, it is with Orontium aquaticum that Calla palustris shares the greatest number of characters: superior ovary, unilocular, tricarpellate gynoecium, basal placentation, and a reticulate pollen. In Orontium, the existence of 6 tepals and 6 stamens was noted while in Calla, 10–12 stamens were observed. It is possible that 6 of the 12 stamens of Calla, correspond to the 6 tepals of Orontium. The subfamily Calloideae is a heterogeneous taxon at the level of floral morphology.

Studies in the Hypoxidaceae. II. Floral morphology and anatomy

The inflorescence and flowers of representatives of Spiloxene, Pauridia and Empodium were studied. The inflorescence shows a reduction from a several-flowered umbel to a single flower. The anthers are non-versatile in all three genera, unlike those of Hypoxis and Rhodohypoxis. In Spiloxene and Pauridia the ovary is 3-locular with axile placentation, while in Empodium it is unilocular with three parietal placentas. The floral vascular anatomy of the three genera is described and the generic differences pointed out. The close relationship between Spiloxene and Pauridia is demonstrated and the inclusion of Pauridia in the Hypoxidaceae is supported. Spiloxene is regarded as generically distinct from Hypoxis.