Which type of aestivation is found in the corolla of cotton?
Twisted aestivation, seen in cotton, occurs when one margin of the petal overlaps the next one.
Ref: NCERT Class 11 Biology chapter - Morphology of flowering plants
#aestivation
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Which type of aestivation is characterized by one petal overlapping the other in one particular direction?
Twisted aestivation, as seen in china rose, occurs when one petal overlaps the next one in a specific direction.
Ref: NCERT Class 11 Biology chapter - Morphology of flowering plants
Vexillary aestivation is characteristic of
Vexillary or descending imbricate papilionaceous aestivation uniquely characterizes family Fabaceae subfamily Faboideae, where broad posterior standard petal vexillum overlaps two lateral wing petals alae which overlap two anterior keel petals carina fused enclosing diadelphous androecium. This hierarchical overlap ensures bee pollination mechanism where keel must be depressed. Solanaceae typically valvate or twisted aestivation in corolla, Malvaceae twisted, Brassicaceae valvate or imbricate not vexillary. Vexillary arrangement co-evolved with zygomorphy and diadelphous stamens forming adaptive complex for legume flower-pollinator coevolution and explosive pollen release upon pollinator tripping.
Ref: NCERT Class 11, Fabaceae vexillary aestivation; Kirkbride, Faboideae floral morphology
Twisted aestivation is seen in
Twisted aestivation also called contorted involves each petal overlapping its neighbour on one side and being overlapped on other side creating spirally arranged corolla resembling pinwheel pattern. Hibiscus rosa-sinensis exhibits prominently twisted corolla with large showy petals, also characteristic of cotton Gossypium and ladies finger Abelmoschus family Malvaceae. Mustard valvate with no overlap, Calotropis also valvate, pea vexillary papilionaceous. Twisted mechanism protects inner androecium in bud and assists rapid unfolding during anthesis via coordinated expansion, conferring structural rigidity to large corolla optimized for pollinator visual attraction and landing platform.
Ref: NCERT Class 11, Twisted aestivation Malvaceae; Judd, Corolla aestivation Hibiscus
Aestivation refers to
Aestivation describes precise spatial arrangement of sepals and petals within same whorl while still enclosed in floral bud, determining overlap pattern crucial for family identification. Valvate margins merely touch without overlap as in mustard, twisted each overlaps neighbor regularly as in Hibiscus, imbricate irregular overlapping as in gulmohur, vexillary posterior largest overlapping as in pea. It differs from inflorescence arrangement which describes flower placement on peduncle, fusion of parts is cohesion adhesion, symmetry actinomorphic versus zygomorphic. Aestivation types serve as stable taxonomic characters reflecting petal packing efficiency and developmental phyllotaxy constraints.
Ref: NCERT Class 11, Aestivation types valvate twisted; Simpson, Aestivation in bud
The floral formula of Fabaceae shows which aestivation?
Fabaceae corolla exhibits descending imbricate or vexillary aestivation where posterior largest petal standard overlaps two lateral wings which in turn overlap two fused anterior keel petals enclosing diadelphous androecium and monocarpellary ovary. This papilionaceous arrangement protects sexual organs and guides pollinator landing, keel depresses to expose stamens. Valvate petals touch without overlap as in Solanaceae, imbricate multidirectional in Cassia, twisted regular overlapping in Hibiscus. Vexillary aestivation is synapomorphy for Faboideae subfamily Papilionoideae and central to pea floral formula ⚥ K(5) C1+2+(2) A(9)+1 G1 with marginal placentation.
Ref: NCERT Class 11 Biology, Fabaceae vexillary aestivation; Starr & Taggart, Papilionoideae floral diagram