. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. 94 TRANSFOBMATIONS OF THE LEAF. 304. The scales wtioh clothe tlie various forms of scale-stems are leaves, or more usually joefo'oZes, reduced and distorted, perhaps by the straitened circumstances of their underground growth. The scales of corms and rhizomas are mostly mere membranes, while those of the bulb are fleshy, serving as depositories of food for the future use of the plant. That these scales are leaves is evident,
. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. 94 TRANSFOBMATIONS OF THE LEAF. 304. The scales wtioh clothe tlie various forms of scale-stems are leaves, or more usually joefo'oZes, reduced and distorted, perhaps by the straitened circumstances of their underground growth. The scales of corms and rhizomas are mostly mere membranes, while those of the bulb are fleshy, serving as depositories of food for the future use of the plant. That these scales are leaves is evident, 1st, from their position at the nodes of the stem, 2d, from their occasional development into true leaves. 305. Bud scales. The brown scales which cover winter buds are of the same nature and origin. 306. The cotyledons of seeds or seed-lobes are readily recognized as leaves, especially when they arise above ground in germination, and form the first pair upon the young plant, as in the beech-nut and squash seed. Their deformity is due to the starchy deposits with which they are crammed for the nourishment of the embryo when germinating, and also to the way in which they are packed in the seed. 307. Phyllodia are certain leaf-forms, consisting of petioles exces- sively compressed, or expanded vertically into margins, while the true lamina is partly or entirely suppressed. Fine examples are seen in our greenhouse acacias from Australia. Their vertical or edgewise position readily distinguishes them from true 1T8 174 17r. 176 177 As-ndia. 173, Nepenthes. 174, Sarraoenia psittaclna. 175, S. purpurea. 170, S. Gronovii, /5. Drummondii. 177, Acacia lieterophylla, its phyllodia. .?08. Asoidia or pitchers, are surprising forma of leaves, expressly contrived, as if hj art, for iiolding water. The pitchers of SaiTacenia, whose several species are common in bogs North and South, are evidently formed by the blending of the in- volute margins of the broadly winged petioles, so as t
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