Stamen lateral

Connation and Adnation.—In the development of the flowers of primitive species of flowering plants, the parts of each whorl are disjoined or separate from each other. In many higher types, however, the parts of the same whorl frequently become partly or completely united laterally. This condition is termed connation, coalescence, cohesion or s)mgenesis. Illustrations of this ihay be seen in Belladonna, Stramonium and Uva Ursi flowers, where the petals have joined laterally to form gamopetalous corollas. When the one or more parts of different whorls are united, as of stamens with petals Rhammus) or stamens with carpels Apocynum) the union is called adnation or adhesion. 

Development of the Anther.—Each stamen originates as a knoblike swelling from the receptacle between the petals and carpels. This swelling represents mainly future soral (anther) tissue. The filament develops later. When such a young sorus or anther is cut... 

In the more benign asexual cycle, Epichloe endophytes (and all Neotyphodium species) remain asymptomatic (Fig. 1). As floral primordia are formed, endophytes grow into ovules, proliferate in the nucellus tissues, and later colonize the embryonic axis of the developing seed, which leads to vertical transmission (Freeman, 1904 Philipson and Christey, 1986). Hyphae in the remnant nucellar layer form a conspicuous mat between the aleuron and the seed coat (White et al., 1991). Symptomless endophytes may also invade stamen filaments and anther walls, but have never been found in pollen grains, and apparently are not disseminated via paternal structures (Sampson, 1933 Hinton and Bacon, 1985). Vertical transmission of endophytes in infected tillers occurs at nearly 100% efficiency (Siegel et al., 1984). However, seeds which are free of endophyte may occasionally be produced when shoot meristems of individual... 

Description Herbaceous, stoloniferous perennial, 5-30 cm tall. Stems compressed, hairy. Leaves in basal rosette, petiolate, trifoliate, margins sharply toothed, lateral leaflets sessile, middle leaflet often short petiolulate. Inflorescence cymose, on an elongated stem. Sepals 5, appressed hairy, margins entire. Petals 5, white. Stamens many. Fruits small achenes, attached to surface of swollen receptacle. Receptacle berry-like, bright red, fleshy, 0.7-2 cm in diameter, elongated or nearly spherical. 

Description Herbaceous perennial with a large, ovate tuber, 5-15 cm wide. Stem 20-60 cm tall, with subterranean part nearly as long. Basal leaves 1 or 2, with 3 petioluled lobes each lobe trisected, middle lobe tripartite with sessile, bisected lateral lobes upper leaves 3-5, lower 2 similar to basal leaves, the most upper leaves smaller and less divided or entire. Inflorescence apical, paniculiform, formed of racemes with 20 0 flowers. Flowers on long, horizontally spreading pedicels. Sepals yellow, petaloid. Petals 6, reduced, yellow. Stamens 6. Fruit an inflated capsule, ca. 15 mm in diameter. Seeds 1-2 per fruit, 5 mm wide, spherical, smooth. 

Other distinguishing features Stamens 10 (9 united). Heads on top of stems and lateral branches. 

The presence of a basally united perianth composed of two distinct perianth whorls, and an androecium with at least one whorl of stamens associated with stalked, presumably nectariferous, structures in Powhatania connata indicates a relationship to extant Laiuales. The stalked structures are distinctive in their shape and position. They are free with semi-peltate/peltate heads and occur in a lateral position to the stamens of the first androecial whorl. 

The subclass Dilleniidae was introduced into angiosperm macrosystematics by Takhtajan (1964) largely influenced by the occiurence of centrifugal stamen initiation in polymerous androecia, which was supposed to be a fundamentally important pattern in macrosystematics. However, the subclass was later dismantled, first by structural cladistic studies (Hufford, 1992) and then also by molecular studies (Chase et al., 1993) (see also Endress et al., 2000). From the present perspective, the feature is not stable at very high systematic levels, however, often it is still at family level. 

Fig 8.2 Peganum harmala. Floral bud, transverse section series. Sepal basal lateral appendages marked with asterisks [ ]. (A) Distal zone, live sepals and five petals with contort aestivation. (B) Fifteen stamens surrounding three carpel tips [c], free but postgenitally united. 

The sepals have three main vascular traces, and there are up to seven branches formed by successive lateral branching (Fig 8.6A-E). The petals and stamens have a single vascular trace (Fig 8.6A-E). In petals, up to ten vascular bundles may be present (Fig 8.6A-D). In carpels the median dorsal vasculature forms a more or less... 

In flowers of Conostegia rhodopetala, C. off. montana, C. xalapensis and Clidemia octona, the secondary increase of the stamens can also occur by a clear process of dedoublement, a phenomenon implying that each or most of the stamens in a flower splits into two parts. Paired stamens are closely adjacent, occasionally laterally fused and occur in antepetalous positions. 

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