BOTANY 



861 



BOTANY 



development and mature form of plant struc- 

 tures, tracing the life history from the single 

 cell to the final complex stage; taxonomy, or 

 classification (see subhead below), which de- 

 pends upon morphology for the facts upon 

 which the arrangement of plants into groups 

 is based; plant anatomy, the study of the tis- 

 sues of which the plant is composed; physiol- 

 ogy, which deals with the functions of the vari- 

 ous organs, leaf, stem, root, and the parts of 

 the flower; and ecology, a somewhat recent 

 phase of the science and an extremely inter- 

 esting one. Itxdeals with plants in relation to 

 their surroundings the changes made in them 

 by changing environments, and the special 

 structures that adapt certain plants to condi- 

 tions which others could not endure. 



Botanical Terms. Anyone in North America 

 who knows anything about trees knows an 

 oak, but the trees which are called by this 

 name differ in size, in manner of growth, in the 

 shape of leaves and acorns, and in other par- 

 ticulars. Some are live oaks, others white oaks, 

 red oaks or bur oaks, but all have an equal 

 right to the name oak. In his scientific naming 

 of plants the botanist takes into account these 

 variations, and calls each different kind a spe- 

 cies (which see). That is, the live oak is a 

 species, and the bur oak is a species; but all 

 the oaks together constitute a larger group, 

 called a genus (which see). The Latin name 

 bestowed upon a plant consists of two parts, 

 the first indicating the genus to which it 

 belongs, the second its particular species. 

 Quercus, for instance, is the Latin word for 

 oak, and is borne by all trees belonging to that 

 genus, but alba, meaning white, is borne only 

 by one species, the white oak. The botanical 

 name for the white oak, therefore, is Quercus 

 alba. 



But all plants which are related are not so 

 closely connected as is one oak with another, 

 and there must therefore be larger groups than 

 the genus. The next higher is the family, 

 which is composed of several or many similar 

 genera (plural of genus) . As pointed out above, 

 members of a family frequently bear no closer 

 resemblance to each other than do members of 

 a human family, and only a botanist can trace 

 their similarities (see FAMILY). Above the 

 family is the order, into which families that 

 have certain resemblances are grouped, and still 

 higher is the class. At the summit of the classi- 

 fication is the division into great groups, of 

 which there are but four in the entire plant 

 kingdom, and these are described below. Very 



definite differences in structure or in habit 

 divide these groups from each other. 



Classification . As botany has been a steadily- 

 growing science, it is natural that the classifica- 

 tion should not have remained stationary ; thus 

 to-day all botanists do not use the same terms 

 or even the same divisions into groups. In the 



h this a 



flower 



or a 



weed ? 



end, however, they all amount to exactly the 

 same thing, and the classification here given is 

 the one acceptable to most scientists. Some of 

 the names are difficult, but in every case ex- 

 planations or alternative terms are given. 



I. Thallophytes (thai 1 ofites), very simple 

 plants without roots, stems or leaves. Some 

 are tiny, one-celled structures, others are large 

 and showy, but none of them produces seed or 

 flowers. To this .lowest of plant groups belong 

 the following forms : 



(a) Bacteria are the simplest of plants. Most 

 people who speak of these as microbes, germs 

 or bacilli do not realize that they are plants as 

 truly as is the greatest oak of the forest. (See 

 BACTERIA. ) 



(b) Algae, or as more commonly named, sea- 

 weeds. These include not merely the seaweeds, 

 properly so called, but the scum which forms 

 on stagnant pools. (See ALGAE.) 



(c) Fungi, including such differing forms as 

 bread mold, water mold, mushrooms and puff- 

 balls. (See FUNGI.) 



(d) Lichens, which partake of the character 

 of both algae and fungi. (See LICHEN.) 



