. The classification of flowering plants. Plants. BROMELIACEAE 279 as in the terrestrial species, or only for fixation, as in the epiphytes; in the latter an adhesive substance is often excreted whereby the plant attaches itself to quite smooth stems. In some cases the Jeaf-bearing stem becomes elongated, forming for instance in Puya a branching structure five to six feet high. The nodes very rarely become much separated, as happens in Tillandsia usneoides (fig. 184), where the long, slender, branched shoots hang in grey lichen-like festoons from the branches of trees ; the adult plant has no
. The classification of flowering plants. Plants. BROMELIACEAE 279 as in the terrestrial species, or only for fixation, as in the epiphytes; in the latter an adhesive substance is often excreted whereby the plant attaches itself to quite smooth stems. In some cases the Jeaf-bearing stem becomes elongated, forming for instance in Puya a branching structure five to six feet high. The nodes very rarely become much separated, as happens in Tillandsia usneoides (fig. 184), where the long, slender, branched shoots hang in grey lichen-like festoons from the branches of trees ; the adult plant has no roots, but the whole surface bears peculiar water-absorbing hairs (F); the shoots become at- ^ tached by winding if^^^^ round the support, leav- ingwhen the softer parts have died away a horse- hair like sclerenchyma- tous strand. Many of the ter- restrial species have branched stolons, which play so important a part in vegetative reproduc- tion that the plants rarely flower and still more rarely bear fruit, for instance the genus Cryptanthus. Certain genera and sections of genera are characterised by much shortened flowering axes, reposing in the centre of the leaf-rosette, and generally encircled by an involucre of brilliantly coloured bracts. The elongated flowering axes may bear leaf-like sterile bracts differing only in colour from the leaves, as in Pine-apple (Ananas) or Billhergia (fig. 135, A), or may form a true scape bearing only a few scale-like bracts immediately below the flowers, as in many Tillandsias. In some cases the flowering axes persist for several years, becoming lignified and producing new inflorescences each successive season. The fertile bracts correspond to the sheath-portion of the leaf They may be. Fig. 135. A. Plant in flower of Billhergia iridifolia, | nat. size. B. Flower of same, slightly reduced. C. Flower cut vertically ; s, septal gland. D. Lower part of petal shewing pair of scales below insertion of stamen. E. Floral Please note th
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectplants, bookyear1904
