BOTANY. 



BOTS. 



tinct,the number of their seeds is often immense : 

 Ray counted 32,000 in one poppy-head ! Where 

 the seeds are less numerous, their safety is se- 

 cured by the extra strength of the seed-vessel, 

 their nauseous, poisonous nature, and other 

 means. The various modes in which they are 

 spread over the face of the country is equal 

 evidence of a peculiar providential care. The 

 seed-down bears some through the air to a dis- 

 tance ; some cling by their rough appendages 

 to the coats of animals ; others are borne by 

 neighbouring streams, or by the winds, to an 

 immense distance; cocoa-nuts float from the 

 tropics to the shores of Norway; African seeds 

 are blown over the southern coasts of Spain ; 

 birds, animals, and even the seed-vessels them- 

 selves, by an ejective power, all perform a part 

 in the office of dissemination. Then, again, 

 the various kinds of defence with which they 

 are endowed : cuticles, woolly, and thorny, and 

 flinty, to preserve an equable temperature and 

 to prevent injurious wounds. The buds which 

 contain the embryo of leaves to appear the 

 following year, how enveloped are they in 

 scales, and often coated with resin or gum ! 



Independent of any general arrangement, 

 plants are divided into species, genera, and 

 varieties. 



By species is to be understood a plant which 

 by certain permanent signs can be distinguished 

 from all others; for instance, every one can 

 determine that the damask rose differs from 

 every other ; and botanists, having shown by 

 what specific marks it may always be distin- 

 guished, have determined it to be a species: but 

 there are many other roses which, though hav- 

 ing specific points of difference, very closely 

 resemble the damask rose ; these, botanists 

 have therefore collected into one family, which 

 they term a genus, under the general name of 

 JJoaa. Rosa, then, is the generic or family 

 31ame; but, to distinguish the species, every 

 ne has a separate second or specific name : 

 thus, the damask rose is Rosa centifolia the 

 dog rose, Rosa canina ; these second names are 

 therefore termed the specific names. By variety 

 is meant a plant varying in an established 

 species, but which cannot produce an exact 

 resemblance of itself by seed. Thus, all our 

 apples are varieties of one species, the crab 

 (Pyrus) ; and all plants raised from their seed 

 invariably differ from each other and their 

 parent The whole vegetable kingdom, then, 

 is divided into families, or genera, composed 

 of a greater or less number of species. In 

 botany the varieties are little noticed. These 

 genera are distributed by Linnaeus into classes, 

 in what, from him, is denominated the Linncean 

 System of Botany. 



These classes are twenty-four in number, 

 founded on the number, situation, or propor- 

 tion of the stamens. 



The plants of the twenty-four classes are 

 farther arranged in subdivisions, denominated 

 orders. The orders of the first thirteen classes 

 are founded on the number of pistils the plants 

 belonging to them contain. 



The orders of the 14th class are distinguished 

 by their seed-vessels. 



The two orders of the 15th class are distin- 

 guished by the form of the seed-vessels. 



The orders of the 16th, 17th, and 18th classes 

 are founded on the number of the stamens, that 

 is, on the characters of the first thirteen classes. 



The orders of the 19th class (Syngenesia) are 

 marked by the nature of the florets. 



The orders of the 20th, 2 1st, and 22d classes 

 are distinguished by the characters of some of 

 the classes that preceded them : that is, by the 

 number or proportion of the stamens, the union 

 of the anthers not being attended to. 



The orders of the 23d class are distinguished 

 upon the principles of the two preceding classes. 



The 24th class (Cryptogamid) is divided into 

 five orders : 



1. Ferns, 3. Liverworts, 



2. Mosses, 4. Algae, 



5. Mushrooms. 



The natural system of M. Jussieu. Every per- 

 son must have observed, that plants in many 

 instances are arranged by nature in families ; 

 for instance, the grasses, liliaceous plants, the 

 umbelliferous plants, mosses, sea-weeds, ferns, 

 &c., are composed of individuals bearing a 

 very striking resemblance to each other in 

 their forms. The same resemblance holds in 

 their internal qualities, between such plants as 

 resemble one another in configuration. Thus 

 the grasses are all nutritious; the liliaceous 

 plants in general poisonous; umbelliferous 

 plants growing on high dry soils are generally 

 wholesome ; those of wet situations are gene- 

 rally poisonous. The importance of keeping 

 these families undivided in a botanical classi- 

 fication is evident; and if plants were univer- 

 sally separable into such distinct families as 

 those above mentioned, a natural system would 

 be easy and perfect. But plants are too diver- 

 sified ; they approach each other in such va- 

 rious shades, that it is certain a complete 

 natural system can never be perfected, or must 

 be too intricate for general use. Jussieu's sys- 

 tem, with all its merit, is open to both these 

 objections ; it is imperfect, were it only from 

 being founded upon the structure of the seed, 

 that part of plants which is, perhaps, more sel- 

 dom than any other capable of being observed 

 by the botanist. 



There are fifteen classes and one hundred 

 orders. The classes have no particular names, 

 but are distinguished by numbers, with a short 

 statement of essential characters. The orders 

 are named after some principal genus in each. 

 There are some inaccuracies in the arrange- 

 ment ; many plants, considered by Jussieu as 

 monocotyledon ous, are now known to be with- 

 out any cotyledons. 



At the end Jussieu places a large assemblage 

 of genera, consisting of plants, the construction 

 of whose seed is undetermined. This, of course, 

 is an imperfection, but not peculiar to Jussieu's 

 system. It must be the case with all systems 

 founded on nature, unless their contrivers 

 could have at once before them a specimen of 

 | every-species of plant that the various portions 

 I of our globe produce. This system has been 

 greatly modified and improved by Decandolle, 

 Lindley, and others ; and it is now justly pre- 

 ferred to the artificial system of Linnaeus. 

 (G. W.Johnson; Dr. Lindley ; G.Sinclair; Trans. 

 High. Soc. vol. i. p. 81.) 



BOTS. In farriery, a kind of worms very 



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