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And from the fact that pitchers are one of the most frequent anomalies, we may conclude that the chance of producing peltate leaves must have been a very great one, and wholly sufficient to account for all observed cases. In every instance the previously existing shape of the leaf must have decided whether peltate or pitcher-like leaves would be formed.
Ascidia of the snake-plantain or Plantago lanceolata are narrow tubes, because the leaves are oblong or lanceolate, while those of the broad leaved species of arrowhead, as for instance, the Sagittaria japonica, are of a conical shape. From the evidence of the lime-tree we may conclude that normal peltate leaves may have originated in the same way.
This plant grows, with a simple tap root, in the deep soft mud, bearing one large peltate leaf on a leaf stalk, about eight feet high, and from twelve to eighteen inches in diameter, the flower-stalk being of the same length or even longer, crowned with a pink flower resembling that of a Nymphaea, but much larger: its seed-vessel is a large cone, with perpendicular holes in its cellular tissue, containing seeds, about three quarters of an inch in length.
They remain flat, become peltate and exhibit a shape which in some way holds a middle position between the pennyworts and the lemon-scented eucalyptus. Here we have the repetition of the specific characters of these plants by the anomaly of another.
It is probable that his seeds were taken partly from normal plants, and partly from hybrids between the normal and the "one-bladed" type, assuming that these hybrids have pinnate leaves like their specific parent, and bear the characters of the other parent only in a latent condition. Our third example relates to peltate leaves.
I have written of a lake, but no water was visible, for it was concealed by thousands and thousands of the peltate leaves of the lotus, nearly round, attaining a diameter of eighteen inches, cool and dewy-looking under the torrid sun, with a blue bloom upon their intense green.
As far as we can judge peltate anomalies are quite uninjurious, while ascidia are forms which must impede the effect of the light on the leaf, as they conceal quite an important part of the upper surface.
Sometimes the peltate leaves are not at all orbicular, but are elongated, oblong or elliptic, and with only the lobes at the base united. The lemon-scented Eucalyptus citriodora is one of the most widely known cases. In other instances the peltate leaves become more or less hollow, constituting broad ascidia as in the case of the crassulaceous genus Umbilicus.
This shrub is principally remarkable for the large, reniform, peltate leaves, which are of value for covering pergolas, bowers and walls. The flowers are of no great account, being rather inconspicuous and paniculate. It is hardy in most places, and is worthy of culture for its graceful habit and handsome foliage. Himalayas, 1842.
In this way it is easily conceivable that peltate leaves are a frequent specific character, while ascidia are not, as they only appear in the special cases of limited adaptation, as in the instances of the so called pitcher-plants. The genera Nepenthes, Sarracenia and some others are very well known and perhaps even the bladderworts or Utricularia might be included here.
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