Floral tube

Perianth - The perianth appears to consist of two alternating, trimerous whorls that are fused into a short floral tube at the base. The outer whorl consists of broad, possibly five-veined, tepals. The inner whorl consists of narrower, three-veined tepals (Fig 3.5G). Scattered gland-like structures, presumably oil glands, are present on the inside of the floral cup (not shown). 

Turner speculated that the two families arose from a common ancestor that likely occupied xeric or halophytic habitats in Gondwana in an area that encompassed what were to become southwestern Africa and southeastern South America. The ancestral types do not still exist, but both families share the unusual, betanidin-based floral chemistry, and the equally unique sieve-tube plastids seen in Caryophyllales but are absent elsewhere in the plant kingdom (Behnke and Turner, 1971). 

It has also been suggested that the betalain- and anthocya-nin-producing families of this order developed from a common ancestor before the widespread occurrence of floral pigments in angiosperms (Mabry, 1976). All families of the Caryophyllales contain sieve-tube cells with proteinaceous inclusions which are not encountered in other plant families. However, because anthocyanins are known from most other groups of plants including gymnosperms and ferns, it seems likely that the ancestors of the Caryophyllales also possessed anthocyanins. 

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. 

Fresh floral buds of Justicia repens L. and Tradescantia sp. were transferred to darkened specimen tubes containing reagent A and the tubes were immediately kept in a refrigerator at 0 to 3 C for about a week. The tissues were washed with three changes of reagent B for 15 minutes in order to remove the excess of silver nitrate. They were then dehydrated using t-butyl alcohol (TBA) series, embedded... 

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