The vegetable kingdom; or, The structure, classification, and uses of plants by Lindley John 1799-1865

Author:Lindley, John, 1799-1865
Language: eng
Format: epub, pdf
Tags: Botany
Publisher: London Bradbury & Evans
Published: 1853-03-25T05:00:00+00:00

I SlXXVII.— Nyiuphwa cosru I

HI an embrj the great plumule lying in the i

N ■

N VMPH.EACE.E.

[Hypogynous Exogens.

It seems, however, desirable to state, in this place, what the reasons are which, hare Se wiS avey confused distribution of fibrovascular bundles among it not at all accoramgw ^ uucl ° , , j^es of fibres are there placed in a con-

to ltf n «toSKiC e ^r2e importance of so-*, «. leost, of these con-aider,'ions ; P „« l'd„ »"« .hint that the, quite dispose of thequest™J- to»h«.j, m.

Fmlncrens as Schleiden first pointed out, and has no resemblance to that of -^gens. ^teafiett derled from internal structure is therefore more in favour of Water-hies bS Endogens than Exogens. The true ground for considering theni Exo-5ens isSainlv confined to the two-lobed embryo. It seems to have been forgotten SwlenTown and Brongniart proved Richard's cotyledon to be nothing, more-than he annuotic sac, they did not also prove, as a necessary consequence, that the so-called SumuTof Sard was a dicotyledonous embryo. It may be monocotyledonous, not^thstandin' its vitellus. Certainly its two lobes are very like those of Exogens ; Eut I toTthat nVymphcea alba the lobes are not suddenly contracted at their base Uke true cotyledons, (no? are they in Nelumbium,) and, moreover that the plumula is, ntthTplan Placed in an oblique direction with respect to the lobes • so that, in fact, L embryo of NySpl-a is much like a modification of such monocotyledonous embryos as thL of Aponogeton, Cymodocea, and Posidoma.-See Ann. Sc. n.s. m(1. Sdeed, I perceive° no re Jon why it should not be regarded ashaving, one spht coSon rather than two distinct ones. The principal mass of the nucleus m the Leas o r6rchids appears from the researches of Professor Link to be an analogous Tasf In these plaL the nucleus is a spheroidal cotyledon, from whose surfaceJhe radicle and plumule respectively protrude. We have only to imagine it elevated on each side and we P should have the twodobed body of this Order. For the present, however, I am not prepared to disturb existing arrangements; though I much suspect tfia

will be done by some other Botanist. Indeed Jtt. Ail. uiong niart has lately declared that the position of Waterhlies appears to him very AoubtiuL—Enumeration xxv. De Lan-doUe assigns as a further reason for considering Waterhlies to be Dicotyledons, that they are lactescent, a property not known in Monocotyledons. But in this he is mistaken ; Lim-nocharis, a genus belonging to Butomads is lactescent Finally, Mr. Hassal appeals to the condition of the pollen ol Waterhlies, which he thinks proves them to be undoubted Monocotyledons. The pollen grain of Nvmphsea is described by this observer as being oval, hispid, with a tur-row down one side, and emitting a single pollen tube, which marks he regards as characteristic of Eudogens.

The germination of Nymphtea alba is not exactly either exogenous or endogenous. The radicle is clearly endorhizal, as in the latter; but the cotyledons lengthen their bases to allow the plumule to escape,

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.