Petal initiation

Fig 9.2 Development of sepals, petals and carpels in Conostegia. (A), (E) C. icosandra (B) C. xalapensis (C) C. pittieri (D), (F) C. macrantha (G) C. rhodopetala (H) C. centronioides. (A) Young inflorescence with older apical flower and two lateral flowers with hracteoles. (B) Partial view of inflorescence with apical flower showing early petal initiation and lateral flower with sepal initiation. (C) Early initiation of gynoecial dome... 

The microstructure of the cement was highly crystalline [9]. Initially, the crystals were petal-shaped and extremely small ( 0.05 p,m in width and 1 pm in length). Subsequently,... 

A facile synthesis of two naturally occurring 3-deoxyanthocyanidins from 2,4,6-triacetoxybenzaldehyde has been described <03S1878>. A one-step route to pyranoanthocyanins, molecules that have been found in red wine <03TL4887>, involves initial reaction under aqueous conditions of cinnamic acids at the electrophilic 4-position of anthocyanins followed by an intramolecular cyclisation and decarboxylation <03TL7583>. A tri-( )-caffeoyl anthocyanin present in the blue petals of morning glory, Ipomoea tricolor, is resistant to ,Z-isomerisation by UV-B irradiation, a property that may be important in plant survival <03TL7875>. 

Clr 34-48 (6Ax 26,500) (6B X 26,500) (6C X 24,000) 83,000 collagen-like domains and petals , globular domains. Globular domains bind Fc regions of IgG and IgM antigen-antibody complexes, leading to activation of Clr and initiation of the classical pathway. Proenzyme to serine protease auto-activates and... 

The perianth has a calyx and corolla in all three genera. In Nitraria and Peganum, the sepals are initiated in a clockwise or anticlockwise spiral sequence. In contrast, the five petals are initiated more or less simultaneously. In both genera, the second sepal is in median adaxial position as is common in core eudicots (this study Payer, 1857 Ronse De Craene, 2010 for Nitraria, also Baillon, 1873 for Peganum, also Eichler, 1878). The abaxial petal between sepals 1 and 3 (= petal 1) is slightly larger than the others at first, in both genera (this study Ronse De Craene et al., 1996). In Tetradiclis the first pair of sepals is in the median plane (Eichler, 1878). 

C. aff. montana, C. suhcrustulata, C. setosa, C. centronioides (Fig 9.2H) and eight to nine slightly asymmetrical petals with a retuse apex in C. macrantha (Fig 9.2C,F), as well as six to seven large petals in C. rhodopetala (Fig 9.2G). Petals are initiated in a rapid sequence on the sides of an invaginating floral apex. The further development of petals is often unidirectional from the abaxial to the adaxial side in all species examined (Fig 9.2C,F). 

Fig 9.5 Flower morphology of Heterocentron elegans (A)-(B), Clidemia octona (C)-(F) and of Dissotis rotundifolia (G)-(ff). (A) Mature flower bud with four petals (removed) and eight stamens. (B) Detail of flower showing a style surrounded by an extension of the ovary wall at the base. The anthers are provided with basal auriculate appendages. (C) Development of sepal lobes surrounding petal primordia. (D) Initiation of stamens and carpels. Note the... 

Fig 11.5 A. celastrifolia, stamen initiation. Sepals and petals removed in all. (A) Frontal view of androecial ring-wall with first stamens formed (asterisks) alternating with the petals. (B) Lateral view of a hud with first formed stamens (asterisks). (C) Androecial ring-wall (circle) and first formed stamens (arrowheads) alternating with the petals. (D) Side view of somewhat older hud. Stamen primordia are formed in a centripetal pattern. 

N. vogelii. (A) Initiation of five corolla lobes on aringprimordium calyx removed. (B) Early initiation of petals. Note the compression by the calyx lobes. (C) Development of lobes on the petals. Note the basally connected area. (D) Lateral extension of lobes on each petal. 

A), (C), (D), (F), (ff) N. imperialis (B), (E), (G) N. vogelii. (A) Apical view at development of second staminodial tier two petals removed. (B) Lateral view of slightly older bud showing initiation of third staminodial tier (arrowhead) two petals removed. (C) Apical view of... 

It is demonstrated that the corona represents a complex structure, which is part corolla and part androecium, represented by two series of distinct staminodes. The argument that the flower is apetalous because of the strong resemblance and association of outer petaloid appendages to the stamen tube gains little support because of the initiation of petal lobes before the androecium and from the fact that petals and stamens are connected by a common stamen-petal tube, which is widespread in asterids. A floral developmental study of genera of Scytopetaloideae, Crateranthus and Astemnthos is expected to confirm the earlier initiation of the outer corolla before the centrifugal development of the androecium. 

Ethylene enhances ABA levels in citrus fruits (Goldschmidt et al. 1973) and in rose petals (Mayak and Halevy 1972). In the latter case the interaction between ethylene and ABA was viewed as an indication that ethylene may initiate senescence by enhancing ABA production and that ABA may, in turn, limit ethylene production by feedback inhibition of its biosynthesis. 

Fig. 245. Circadian opening (rising of the curve) and closing (falling of the curve) of the petals of Kalanchoe blossfeldiana. After initial setting by light-dark alternation, the succession of movements can be maintained in constant darkness (modified from Running 1967).

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