The elements of botany : structural and physiological : with a sketch of the artificial modes of classification, and a glossary of technical terms / by John Lindley.

John Lindley

Date:: 1861

Credit: The elements of botany : structural and physiological : with a sketch of the artificial modes of classification, and a glossary of technical terms / by John Lindley. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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$XIII.—OF THE FLORAL ENVELOPES. 392. The Floral Envelopes are the parts which immediately surround the sexual organs. 393. They arc formed of one or more whorls of hracts, and are therefore modified leaves (343). 394. In anatomical structui-e they do not essentially differ from the leaves, farther than is necessarily consequent u])on the peculiar modifica- tions of size or development to which they are euhject. 395. When the floral envelopes consist of bul one whorl of leaves, they are called calyx. 39G. When two or moi'e whorls are developed, the outer is called calyx, the inner corolla. 397. There is no other essential difference between the calyx and corolla. Therefore, when a plant has but one floral envelope, that one is calyx, whatever may be its colour or degree of development. Tliat there is no other difference between them than one of development, is curiously shown by what is called the Apetalous Apple, in which the petals never grow beyond the condition of the sepals 398. It is necessary, however, to be aware, that some- times tlie calyx is reduced to a mere rim, either in conse- quence of lateral compression, as in the pappus [aigrette, Fr.) of many Composites, or from other unknown causes, as in some Acanthads. It may be assumed, perhaps, that in these cases the growth of the calyx is arrested before its component parts have time to separate; for the observations which have been made upon Organogenesis, show the floral organs usually to appear in the foiTO of a ring or cup, and to divide afterwards. 399. If the floral envelopes are of such a nature that it is not obvious wliethor they consist of both calyx and corolla, or of calyx only, they receive the name of perianth or perigone. 400. Plants have frequently no floral envelopes ; in tbat case flowers are said to be naked or achlamydeous. There is in reality every degi-ee of ^e=v ^ complication between flowers con- Iff'Bji |(Q9J) ^ ^ sisting of a great number and J \ J ^ variety of parts, and the absence j_,.3 of everything excepting bracts and sexes. The accompanying diagram is given by M. Adr. do Jussiou, for the purpose of exemplifying this sort of de(jradation ; that on the left hand showing a flower with 3 sepals and 3 stamens, those on the right a single bract and stamen or caipel. 401. When the floral envelopes are deciduous, they fall from tlie peduncle, as loaves from a branch, by means of an articulation ; if they are persistent, it is because no articulation exists. 402. When the margins of floral envelopes are united, the part where the union has taken place is called the tuhe, and that where they are sepa-$