The primary trimerous pattern of the flower of Echinodorus amazonicus Rataj is clearly exhibited in the earliest developmental stages. After the inception of three sepals, theree alternisepalous petal‐stamen complexes arise, each of which, at successively higher levels of the primordia, consists of a petal, a pair of stamens, and a single stamen. In alternation with these three petal‐stamen complexes three groups of three pistil (carpel) primordia are formed. Subsequent pistil primordia are formed rapidly in alternation with the preceding ones. Teratological buds were observed in which one pistil primordium appeared to be replaced by a normal stamen primordium. General features of the flowers of the Alismatales are summarized in developmental fashion which includes the mature flower as a final stage. With the exception of Limnocharis and probably Wisneria, all alismatalean flowers appear to be characterized by antipetalous stamen (or staminodial) paris. In members studied thus far, the basic trimery differs radically from that found in certain taxa of the Magnoliidae.

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The net consequence of nectar robbing on reproductive success of plants is usually negative and the positive effect is rarely produced. We evaluated the influence of nectar robbing on the behaviour of pollinators and the reproductive success of Tecomella undulata (Bignoniaceae) in a natural population. Experimental pollinations showed that the trees were strictly self-incompatible. The three types of floral colour morphs of the tree viz. red, orange and yellow, lacked compatibility barriers. The pollinators (Pycnonotus cafer and Pycnonotus leucotis) and the robber (Nectarinia asiatica) showed equal preference for all the morphs, as they visited each morph with nearly equal frequency and flower-handling time. The sunbirds caused up to 60% nectar robbing, mostly (99%) by piercing through the corolla tube. Although nectar is replenished at regular intervals, insufficient amount of nectar compelled the pollinators to visit additional trees in bloom. Data of manual nectar robbing from the entire tree showed that the pollinators covered lower number of flowers per tree (5 flowers/tree) and more trees per bout (7 trees/bout) than the unrobbed ones (19 flowers/tree and 2 trees bout). The robbed trees set a significantly greater amount of fruits than the unrobbed trees. However, the number of seeds in a fruit did not differ significantly. The study shows that plant-pollinator-robber interaction may benefit the self-incompatible plant species under conditions that increases the visits of pollinators among the compatible conspecifics in a population.

The primordia of the floral appendages are initiated in acropetal order. They develop in the same order in which they appear but for the petals, which are retarded in their early growth and mature rapidly shortly before anthesis. While the sepal primordia are dorsiventral from their inception, the primordia of other appendages are of nearly radial symmetry and become more or less dorsiventral in their later stages of development. Each petal primordium together with the primordia of a stamen pair arise on one common petal–stamen (CA) primordium. The many pistil primordia arise on three antesepalous gynoecial bulges and the area between them. Thus, in its development the flower exhibits primarily a tricyclic trimerous plan. The floral apices have a two-layered tunica up to the stage of pistil inception. The initiation of all floral appendages occurs by periclinal divisions in the second layer. The third layer (corpus) may contribute, especially in the case of the petal–stamen primordia and the gynoecial bulges. The development of procambium is acropetal. Each primordium receives a single procambial strand shortly after its initiation. Thus, procambial differentiation occurs as a response to primordial inception and not according to the principle of the conservatism of vascular tissue. Additional procambial strands may differentiate as a response to increase in size. The relationships of Alisma to some ranalian families are discussed. Since the floral pattern of Alisma may be considered as a secondary derivation from a trimerous pattern, it does not appear primitive at all. Other primitive features such as apocarpy and lack of fusion of pistil margins are however retained. Thus, Alisma is a good example for heterobathmy.

Context: Syzygium cumini (L.) Skeels (Myrtaceae), commonly known as jamun, is an Indian plant, traditionally well known for its medicinal properties including antidiabetic activity. Objective: To isolate the antidiabetic compounds from Syzygium cumini seeds and evaluate their activity using aldose reductase (AR) and protein-tyrosine phosphatase 1B (PTP1B) inhibition assays. Materials and methods:The dried seeds were extracted with methanol and partitioned with ethyl acetate, butanol, and water. The extracts were screened for antidiabetic activity at a concentration of 100 mg/mL using in vitro AR and PTP 1B inhibition assays. Results and discussion: The highly enriched fractions obtained from broad ethyl acetate fraction yielded maslinic acid (1), 5-(hydroxymethyl) furfural (2), gallic acid (3), valoneic acid dilactone (4), rubuphenol (5), and ellagic acid (6). Structures were elucidated by 1 H-NMR and 13 C-NMR. The initial ethyl acetate fraction showed AR inhibitory activity with the IC 50 value of 2.50 mg/mL and PTP1B enzyme inhibition with the IC 50 value of 26.36 mg/mL. Compounds 3, 4, 5, and 6 were found to inhibit AR with IC 50 values of 0.77, 0.075, 0.165, and 0.12 mg/mL while the compounds 4, 5, and 6 inhibited PTP1B with IC 50 values of 9.37, 28.14, and 25.96 mg/mL, respectively. Conclusion:The results of this study demonstrate that the isolated constituents show promising in vitro antidiabetic activity and, therefore, can be candidates for in vivo biological screening using relevant models to ascertain their antidiabetic activity.