. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. 62 MORPHOLOGY OF ANGIOSPERMS. A The archesporial cells behave as do those of the microspo- rangium, ana in ease the archesporium is a plate of cells, the resemblance is striking. In the large majority of cases, haw- ever, the archesporium is a single cell, and often by transverse division it gives rise to a primary parietal cell and a primary sporogenous cell (Fig. 26). That the former cell, or plate of cells, as it is in the case of a several-celled archesporium, repre- sents the primary pariet
. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. 62 MORPHOLOGY OF ANGIOSPERMS. A The archesporial cells behave as do those of the microspo- rangium, ana in ease the archesporium is a plate of cells, the resemblance is striking. In the large majority of cases, haw- ever, the archesporium is a single cell, and often by transverse division it gives rise to a primary parietal cell and a primary sporogenous cell (Fig. 26). That the former cell, or plate of cells, as it is in the case of a several-celled archesporium, repre- sents the primary parietal layer of the microsporangium seems- clear. In recognition of this fact Strasburger called it the " tapetal cell," hilt for reasons given under the microsporangium we shall call it the parietal cellâthat is, a cell that develops in part the wall of the em- bedded sporangium. Mottier 2S has reported a very peculiar case in Ari- saema, in which the single archespo- rial cell divides by anticlinal walls into three or four cells, each of which then cuts off a parietal cell. Just how far this is exceptional behavior remains to be seen, but it intro- duces an interesting problem as to the application of the term archespo- rium. The behavior of the primary parietal cell is exceedingly varied. An extreme case is for a series of sporial cell has given rise to pri- periclinal divisions to occur, result- mary parietal cell (t) and pri- â _ ⢠â -i â o â , ^ -,, 1 ii , , mS ln a long row of parietal cells, mary sporogenous cell (m).â ° ° ' After Chambeklain.*" corresponding to the parietal layers of the microsporangium. In case there is a plate of archesporial cells the radial rows of parietal cells are very conspicuous, as in the Rosaceae and many of the Amentiferae (Figs. 23, B, /), E). In other cases the parietal rows become lost by the formation of anticlinal walls. If the mother-cell broadens rapidly, the first divisions of the pri- mary parietal coll ma
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