Stamen development

Alves-Ferreira M, Wellmer F, Banhara A, Kumar V, Riechmann JL, Meyerowitz EM. 2007. Global expression profiling applied to the analysis of Arabidopsis stamen development. Plant Physiol 145 747-762. 

The flowers of most species have six sepals, arranged in two cycles. Sepals are the outermost whorl of a flower, typically leaf-like in appearance. The stamens, or male organs, of laurel flowers occur in three or four cycles, with three stamens in each. The flowers usually have a single pistil, or female organ, which contains a single ovule that develops into a seed after fertilization. The fruit of most species is aromatic, and is classified as a drupe, in that is has a fleshy outer layer and a hard inner layer with a single seed. 

In both the flowers develop at least two sets of leaves (either on one or two plants of the same species) called sporophylla or sporophyll leaves, the stamens and carpels. The stamens or stam-inal leaves are also termed microsporophylls. The carpels or carpellate leaves are alscx known as megasporophylls. 

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... 

II. Order Principles.—Palmew or Palm Family.—Tropical or subtropical shrubs, rarely trees, having unbranched trunks which are terminated by a crown of leaves, in the axils of which the flowers are produced. The leaves are well developed with pinnate or palmate blades and a fibrous sheathed clasping petiole. The flowers are small, of one or two sexes, and crowded on a spike or spadix, which is subtended by a large bract, or spathe which may become woody, as in the Cocoanut Palm. The perianth consists of 6 parts in 2 whorls (3 sepals and 3 petals) or it may be inconspicuous or absent. The stamens are 6 in number, rarely 3, inserted below the ovary. The ovary is superior, of 3 cells, with central placenta. The fruit is either a nut, with leathery epicarp, fibrous or cellular mesocarp and thin membranous endocarp, or a drupe (Cocoanut) with leathery epicarp, broadly fibrous mesocarp and stony endocarp, or a berry as in the Date Palm, Phoenix, with membranous epicarp, succulent mesocarp and soft succulent endocarp. The seeds are albuminous with the reserve food frequently in the form of hard cellulose (ivory-nut-palm). 

The disk may be very thin and inconspicuous, lining the inside of a hypanthium, or forming a thickened base for the ovary, when more developed it may be annular, cushionshaped, broken up in patches, and so on. By position relative -to the stamens it is calladi... 

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... 

The opium alkaloid content of P. somniferum varieties cultivated in Bulgaria and in Hokkaidohas been determined. The effects of planting density on yield of alkaloids and of climatic variations on the accumulation of morphine in this species have been noted.A Swedish variety has been bred to produce a low morphine content. The alkaloids present in the stamens of P. somniferum at different stages of their development have been examined. Evidence has been produced that the alkaloids are produced, stored, and translocated in the vacuolar sap of the vesicles present in the latex of P. somniferumThe thebaine content of P. bracteatum at various times in the growing season and a g.l.c. method of... 

Leaves show considerable variation in size, shape, arrangement of veins, type of attachment to the stem, and texture. They may be simple or divided into leaflets, i,e, compound (see illustration), Types of leaf include cotyledons (seed leaves) scale leaves, which lack chlorophyll and develop on rhizomes or protect the inner leaves of a bud foliage leaves, which are the main organs for photosynthesis and transpiration and bracts and floral leaves, such as sepals, petals, stamens, and carpels, which are specialized for reproduction. 

In belladonna plants deuteration had a drastic effect on flower development (25). The number of calyx lobes, corolla lobes, and stamens, while invariably 5 in control flowers, increased to as many as 9 or 10 in plants grown in 70 percent D2O medium. Abnormally shaped berries formed in plants grown in heavy water. The extent of malformation depended,on the D2O content of the medium and how late in the life cycle of the plant that the berry formed. The shapes ranged from pear-shaped to dumbbell-shaped to cylindrical. The misshapened berries resulted from the tenacity with which the corolla remained attached to the ripening berry in deuterated plants. As the berry enlarged, a constriction developed where the corolla was attached to the berry. The size and number of seeds were severely reduced in deuterated berries with only a few rudimentary seeds apparent in the 70 percent berries. 

Floral development and morphology of Vochysiaceae. II. The position of the single fertile stamen. American Journal of Botany, 90,1548-1559. 

---