Book I. 



DISTRIBUTION OF VEGETABLES. 



269 



1746. A third subdivision of aquatics is that of paludal or fen plants, being such as are peculiar to 

 lakes, marshes, and stagnant or nearly stagnant waters, but of which the bottom is often tolerably clear. 

 In such situations you find the Isofetes lacustris, flowering rush, water ranunculus, water violet, and a 

 variety of others, which uniformly affect such situations; some of them being wholly immersed, and others 

 immersed only in part. 



1747. Earthy soils are such as emerge above the water, and constitute the surface of 

 the habitable globe, vv^hich is every where covered with vegetable productions. Plants 

 affecting such soils, which comprise by far the greater part of the vegetable kingdom, 

 are denominated terrestrial, being such as vegetate upon the surface of the earth, without 

 having any portion immersed in water, or requiring any further moisture for their 

 support beyond that which they derive from the earth and atmosphere. This division is, 

 like the aquatics, distributed into several subdivisions according to the peculiar situations 

 which different tribes affect. 



1748. Some of them are maritime, that is, growing only on the sea-coast, or at no great distance from 

 it, such as 5tatice, Glaux, Samolus, samphire, sea-pea. 



1749. Some are fluviatic, that is, affecting the banks of rivers, such as L^thrum, Lycbpus, Z;upatbrm?. 



1750. Some are champaign, that is, affecting chiefly the plains, meadows, and cultivated fields, such as 

 Cardamine, T'ragopijgon, Agrostemma. 



17.^1. Some are dumose, that is, growing in hedges and thickets, such as the brambla 

 1752. Some are ruderate, that is, growing on rubbish, such as Senfecio viscijsus. 



- 1753. Some are sylvatic, that is, growing in woods or forests, such as 5tachys sylvatica, Angelica syl- 



vestris. 

 1754. And, finally, some are alpine, that is, growing on the summits of mountains, such as Poa alpina, 



Epilobium alpinum, and many of the mosses and lichens. 



1755. Vegetable soils are such as are formed of vegetating or decayed plants themselves, 

 to some of which the seeds of certain other plants are found to adhere, as being the only 

 soil fitted to their germination and developement. The plants springing from them are 

 denominated Parasitical, as being plants that will vegetate neither in the water nor earth, 

 but on certain other plants, to which they attach themselves by means of roots, that pene- 

 trate the bark, and from the juices of which they do often, though not always, derive 

 their support. This last circumstance constitutes the ground of a subdivision of parasi- 

 tical plants, into such as adhere to the dead or inert parts of other plants, and such as 

 adhere to living plants, and feed on their juices. 



1756. In the first subdivision we may place parasitical mosses, lichens, and fungi, which are found as 

 often, and in as great perfection, on the stumps of rotten trees, and on rotten pales and stakes, as on trees 

 which are yet vegetating ; whence it is also plain that they do not derive their nourishment from the juices 

 of the plants on which they grow, but from their decayed parts, and the atmosphere by which they are 

 surrounded ; the plant to which they cling serving as a basis of support. 



1757. In the second subdivision we may place aWplants strictly parasitical, that is, all such as do actually 

 abstract from the juices of the plant to which they cling the nourishment necessary to the developement 

 of their parts ; and of which the most common, at least as being indigenous to Britain, are the mistletoe, 

 dodder, broom-rape, and a sort of tuber which grows on the root of saffron, and destroys it if allowed to 

 spread. 



1758. The mistletoe {Viscum album) is found for the most part on the apple tree; but sometimes also 

 on the oak. If its berry is made to adhere to the trunk or branch of either of the foregoing trees, which 

 from its glutinous nature it may readily be made to do, it germinates by sending out a small globular body 

 attached to a pedicle, which after it acquires a certain length bends towards the bark, whether above it or 

 below it, into which it insinuates itself by means of a num- 

 ber of small fibres which it now protrudes, and by which it 

 abstracts from the plant the nourishment necessary to its 

 future developement. When the root has thus fixed itself 

 in the bark of the supporting tree, the stem of the para- 

 site begins to ascend, at first smooth and tapering, and of 

 a pale green colour, but finally protruding a multiplicity 

 of branches and leaves. It seems to have been thought 

 by some botanists that the roots of the mistletoe penetrate 

 even into the wood, as well as through the bark. But the 

 observations of Du Hamel show that this opinion is not 

 well founded. The roots are, indeed, often found within 

 the wood, which they thus seem to have penetrated by 

 their own vegetating power : but the fact is, that they are 

 merely covered by the additional layers of wood which have 

 been formed since the fibres first insinuated themselves 

 into the bark. 



1759. The Cuscuta europce^a, or dodder (^g.20O.), though 

 it is to be accounted a truly parasitical plant in the issue, is 

 yet not originally so. For the seed of this plant, when it 

 has fallen to the ground, takes root originally by sending . 

 down its radicle into the soil and elevating its stem into 

 the air. It is not yet, therefore, a parasitical plant. But 

 the stem which is now elevated above the surface lays hold 



of the first plant it meets with, though it is particularly _ 



partial to hops and nettles, and twines itself around it, attaching itself by means" of little parasitical roots, 

 at the pomts of contact, and finally detaching itself from the soil altogether by the decay of the original 

 root, and becoming a truly parasitical plant. Withering describes the plant in his Arrangement as being 

 ongmally parasitical ; but this is certainly not the fact. 



1760. The Orobdnche, or broom-rape, which attaches itself by the root to the roots of other plants, is 

 also to be regarded as being truly parasitical, though it sometimes sends out fibres which seem to draw 

 nourishment from the earth. It is found most frequently on the roots of clover and common broom, but 

 also in various other places. 



1761. The Epidendrum fids aeris is regarded also by botanists as a parasitical plant, because it is generally 

 found growing on other trees. But as it is found to grow in old tan, it probably derives only support from 

 the bark of trees, and not nourishment. 



1762. Light is a body which has very considerable influence on the structure of vege- 



