Pollination Mechanisms :salvia, calotropis, ficus, orchid, vallisneria and papilionaceous.
(a)
SALVIA(Labiatae)-In
Salvia sp. cross-pollination by insects (bees) is brought about by special elaborate development of morphological structures in the androecium. The stamens, numbering two are provided with long connective, the anterior end of the connective forms a knob at the end of arm-thus a lever arrangement with spring action has been elaborated ; the lower lip of
Salvia forms a landing stage for insects e.g. bees. Honey is secreted in the lower side of the hypogynous disc. The single anther lobe of stamens is concealed in the head-like upper lip. A bee in search of nectar sits on the lower lip, then in attempting to get nectar it touches the knob of sterile anther, as a result of which the upper fertile anther lobe strikes on the back of the bee. The back of the bee is thus dusted with pollens. The style with forked stigmas forms a bent-structure. AS the bee With the pollen powder on its back enters another mature flower, the Pollen powders are caught by the forked recurved stigmas from the back of the bee. The flowers of Salvia are highly protandrous and have corolla arrangement of 2/3 type i.e upper lip of 2 lobes and lower of 3 lobes.
(b)In
calotropis sp. too there is a highly elaborate arrangement for cross pollination by means of isects (bees). The corona-like appendages are associated with the secretion and storing of nectar in
Calotropis. The dust isn't granular yet accumulated into two waxy masses-the alleged pollinia which are appended with each other by slim stalk-like procedures known as interpreters which end in scored handle like structure, the corpusculum. Stamens and pistils are follower to frame gynostegium. The anthers are disciple on the sidelong sides of the pentangular disgrace. There are little openings or openings between the adjoining cells of anthers. A bee or other insects in search for nectar comes in contact with the notched corpusculum which comes out partially through the slits of anthers. The corpusculum is hygroscopic, it is caught by the leg of the insect firmly. The creepy crawly while resigning from the flower hauls with it the entire pollinia connected to its leg and on visiting another flower then pollinia are saved on the glue shame of the same. Thus cross pollination by insect is easily brought about.
(c)
FICUS (Moraceae)-In
Ficus sp., the small flowers are almost enclosed by the receptacle of the hypanthodium, but there exists a small opening through which small insects (gall wasps) enter. Ecological adaptation has arisen in Ficus for ensuring cross-pollination by insects.The hypanthodium contains three kinds of flowers-the male flowers and two kinds of female flowers-one with short styles called gall flowers which are sterile and the others with long styles which are fertile. Pollination is brought about by means of very small wasps, the so-called gall wasps (Blastofaga) which enter the hypanthodium through its small apical pore to lay their eggs in the ovaries of gall flowers. As the male flowers are there, the bodies of wasps are dusted with pollens ; the wasps on entering another hypanthodium come in contact with the styles of fertile female flowers, thus cross-péllination is effected.
(d)
ORCHID (Orchidaceae)--The highest adaptation for cross-pollination by insect agency is developed in the flowers of
orchid. The labellum or lip acts as flag apparatus as well as landing stage for insects. Besides there are various complexity in the organisation and construction of other floral parts which play an important role in the transference of pollen. The rostellum (the posterior sterile stigmatic lobe) forms a viscid disc which secretes a sticky fluid so that entire pollinia adhere to the body of insects. The pollinia with caudicles and corpusculum are also adaptations for entomophily in Orchids.
(e)
VALLISNERIA (Hydrocharitaceae)-Refer in Agents of pollination (hydrophily) (2)
(f)
PAPILIONACEOUS FLOWER-In
Papilionaceae the construction of the flower itself is an adaptation for cross-pollination by insects. The standard is the flag apparatus, the wing-petals are the landing stage for insects. The flower is so constructed that the weight of the insect on wing petals causes the keel to come down-as a result the hidden stigma within the sheathing filament jerks out and consequently comes in contact with the pollen-dusted body of the insect.
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