. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. 50 MORPHOLOGY OP ANGIOSPBEMS phora, suggests the explanation. Lotsy finds that the enlarged tip of the flower axis soon completely fills the cavity of the ovary, and that one or more hypodermal cells of this axis form the mega- spores (Fig. 20). This is exactly the case of Loranthus, and suggests that in the allied Balanophora the same " mamelon" is present, but with no carpellary investment, the naked nucellus (as the " mamelon " would seem to be in this case ) de- veloping
. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. 50 MORPHOLOGY OP ANGIOSPBEMS phora, suggests the explanation. Lotsy finds that the enlarged tip of the flower axis soon completely fills the cavity of the ovary, and that one or more hypodermal cells of this axis form the mega- spores (Fig. 20). This is exactly the case of Loranthus, and suggests that in the allied Balanophora the same " mamelon" is present, but with no carpellary investment, the naked nucellus (as the " mamelon " would seem to be in this case ) de- veloping the remarkable neck-like outgrowth of sterile tissue. In both families it seems certain that the megasporangia are cauline. Foliar ovules are related to the carpels in a variety of ways. By far the most common position is for the ovules to arise in a line along each side of one of the two prominent vas- cular bundles of the carpel, a very common position for the sporangia of ferns. In the older morphology this line was thought to represent the abutting margins of the infolded car- pellary leaf, and hence such ovules were called " ; In fact, this double line of ovules, ami the dehiscence of many carpels along it, seemed to the supporters of meta- morphosis to prove the foliar nature of the carpel. As might be expected from the behavior of sporangia in ferns, there are cases in which mules arise without such close connection with a prominent vascular bundle. For example, in Butomus, Nymphaea, Nuphar, Obolaria, Barionia, and many species of Gentiana, the ovules arise from the whole inner surface of the carpel. In the older terminology these were called " super- ficial " ovules, and associated with them, curiously enough, were. B Fig. 19.—Loranthus sphaerocarpus, A, longitudinal section of a young flower showing the "mamelon" (m); x 25. -Z>, longitudinal sec- tion of a u mamelon " at a later stage showing two hypodermal archesporial
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Keywords: ., bookauthorcoulterj, bookcentury1900, bookdecade1900, bookyear1903
