. A textbook of botany for colleges and universities ... Botany. REPRODUCTION AND DISPERSAL 893 ^^ if an inflorescence is cut off and allowed to strike root in a moist chamber the tip grows into a vegetative shoot (figs. 1199, 1200). The oldest buds develop into the usual flowers, while younger buds de- velop into cleistogamous flowers without prominent corollas; still younger buds develop only the calyx, and the very youngest lateral buds, as well as the ter- minal bud, develop vegetative shoots. If a flowering shoot of Myriophyllum heierophyllum is transferred from a pond to a covered aquari
. A textbook of botany for colleges and universities ... Botany. REPRODUCTION AND DISPERSAL 893 ^^ if an inflorescence is cut off and allowed to strike root in a moist chamber the tip grows into a vegetative shoot (figs. 1199, 1200). The oldest buds develop into the usual flowers, while younger buds de- velop into cleistogamous flowers without prominent corollas; still younger buds develop only the calyx, and the very youngest lateral buds, as well as the ter- minal bud, develop vegetative shoots. If a flowering shoot of Myriophyllum heierophyllum is transferred from a pond to a covered aquarium, it becomes transformed into a vegetative shoot. Ajuga repians has three phases, a rosette, a flowering shoot, and a stolon, and any of the three can be induced at any time by supplying the requisite ex- ternal conditions. If the flowers of Opuntia are removed from the plant and placed in the soil, they soon strike root and give rise to vegetative shoots. Most striking of all, perhaps, are the reactions of the xerophyte, Sempervivum, which also has three phases, comparable to those of Ajuga; vegetative activity may be made to continue indefinitely, stolon formation may be eliminated, and phenomena unusual in nature (such as rosette for- mation at the stem apex, and the transformation of the inflorescence into a vegetative shoot) may be induced at will. Reversibility of stages is not confined to the seed plants; if a fruiting shoot of Selaginella lepidophylla is cut off and placed in the soil of a moist hothouse, it be- comes transformed into a vegetative shoot, even developing rhizophores. Reversi- bility can be induced also in animals, for if a polyp of the hydroid. Campanularia, is brought into contact with a sohd body, it gradually becomes undifferentiated and finally develops into a stolon, whereas removal to the original habitat soon results in a transformation back to a polyp. It may be noted finally that reversibility is the usual thing in the pineapple, a vegetative
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
