Rao et al. (1954), Rao and Pai (1959, 1960), and Rao and Gupta (1961) studied the floral anatomy of the members of Scitamineae, in which a few species of Zingiber were also included. The floral anatomy of Z. ottensi, Z. macrostachyum, Z. cernuum, and other Zingiber species was reported by these workers. Because of the basic similarities in floral characters, it is presumed that the floral anatomical features will also be identical. The following discussion is based on the reports of the above-mentioned workers. The floral anatomical features of Z. cernuum (which is different from Z. officinale only by the absence of staminodes) are given in Figure 2.9. The peduncle contains two rings of vascular bundles with a few strands in the central pith. The inner ring gives off three dorsal bundles of the carpels outward and the latter then divide into three large strands alternating in position with the dorsal bundles of the carpels. The central strands unite
first into one bundle for a short length and fuse with the vascular tissue immediately to the outside. The three large bundles divide first into smaller inner placental bundles and a large outer parietal bundle. The placental bundle may branch off almost at its base. The parietal bundle travels into the septa and sends a few outward branches into the ovary wall. The placental bundles in the axile area bear the ovular traces. The posterior parietal bundle is larger and divides even at a lower level than the other two into two or three. A transverse section through the basal part of the ovary at this level shows: (1) a comparatively thick ovary wall in which there are numerous vascular bundles almost irregularly scattered, (2) in each of the three septa there is a prominent bundle that may divide into two, and (3) in the placental zone there are 6 to 10 strands that bear traces for the ovules. Most of the potential bundles are exhausted in supplying the ovules while one or two may fuse with the nearest parietal bundle. The loculi extend for a considerable distance above the ovuliferous zone, and in this terminal part of the ovary the number of bundles in the ovary wall is reduced by fusions among themselves, and all of them form almost a single ring near the level where the loculi end. Just on the top of the ovary, the three parietal strands, which have already divided into two or three bundles, extend laterally and form a broad network-like cylinder of vascular tissue. This network establishes vascular connections (anastamoses) with the peripheral bundles. The three loculi continue upwards into a Y-shaped stylar canal. After the anastamosis the vascular tissue directly forms (1) an outermost ring of about 15 small bundles for the calyx, (2)
a next inner ring of about 25 larger strands for the corolla and androecial members, and (3) toward the center a number of small scattered strands arrange somewhat in the form of an arc. Two stylar traces are given off from the two margins of this arc-like group and they stand close to the two arms of the Y-shaped stylar canal. The numerous small bundles, arranged at first as an arc, break up into two groups, which supply the two epigynous glands present in anteriolateral positions. The tubular basal parts of the calyx containing the sepal traces referred to earlier are at first separated, and at the same level, the two epigynous glands also separate. A very short distance above, the style also separates.
The basal part of the floral tube contains a ring of vascular bundles, an additional bundle in the median posterior position, and a pair of closely placed bundles on either side. The median posterior strand and the double strands on either side constitute the supply to the functional stamen. One of the component bundles of each double strand divides into two in such a way as to result in a third bundle that lies toward the inner side with its xylem pointing to the outside. On the anterior side of the floral tube, the vascular bundles divide and form two rings, whereas on the posterior face, external to the stamen traces, there is only one ring of bundles. The latter are for the labellum, whose margins are fused for a short distance with those of the filament. The outer ring of bundles is for the corolla.
The flat filament receives: (1) a small median bundle; (2) a triple strand on either side of it, the constituent bundles of which more or less fuse together; and (3) two or four minute strands toward either margin. The lateral triple strands are opposite the line of attachment of the anther lobes to the filament. The minute marginal traces disappear quickly, leaving only a small median bundle and the two lateral large composite ones. These run in parallel manner upward, and the composite strands of each lateral group fuse together more or less completely, so that the anther connective contains a small median and two large lateral bundles. Above the level of the anther, the connective is continued upward as a narrow flat plate with margins incurved and enclosing the style. Each of the two composite lateral strands becomes smaller and divides into two. Thus, in the terminal part of the filament, five bundles are present, of which one is the median one. The median bundle fades out first, leaving a pair of bundles on either side. The bundles of each pair then fuse together giving only two bundles, which run right up to the tip and disappear.
The style receives only two traces and these run throughout its length without any branching. The styled canal is narrow, Y-shaped, the arms of the Y pointing to the posterior side. Toward the tip the arms of the stylar canal spread out so that the canal appears as a curved slit in transverse sections. It then widens out into a large canal, which opens freely to the outside. The two vascular bundles of the style become more prominent in this terminal part and then disappear (Rao and Pai, 1959).
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