This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Amongst British wild plants some genera are more liable to hybridize than others. Exactly which are species and which are hybrids, indeed, is not certainly known. Willow hybrids are generally fertile, and have been universally accepted as such. Many so-called species of Mentha are sterile hybrids, and are largely reproduced by suckers. It is also not clear whether some genera do not include some hybrids that are usually sterile and others that are fertile. Formerly hybrid varieties were held to be fertile, hybrid species sterile, but this view needs some modification to-day.
Amongst British genera hybrids occur, e.g. in Ranunculus, Papaver, Cardamine, Helianthemum, Viola, Silene, Lychnis, Hypericum, Medicago, Rubus, Geum, Rosa, Drosera, Epilobium, Galium, Erigeron, Senecio, Carduus, Hieracium, Vaccinium, Erica, Limonium, Primula, Gentiana, Pulmonaria, Verbascum, Linaria, Euphrasia, Mentha, La?nium, Polygonum, Rumex, Daphne, Betula, Ulmus, Quercus, Salix, Populus, Orchis, Ophrys, /uncus, Potamogeton, Scirpus, Carex, Alopecurus, Poa, Festuca, Lolium, Agropyron.
One of the greatest cruxes the beginner has to face in studying British plants is how to name his specimens. Identification, in a word, is a great bugbear to many a young student. As a matter of fact, a good deal of preliminary botanical work is required before identification should be attempted. Unfortunately this is hardly realized by nine out of ten whose ambition it is to acquire a knowledge of the British Flora. Consequently the accomplishment of this ideal spreads itself over a far longer period than if a solid basis of botanical knowledge had been gained beforehand. Probably very few British botanists have been able to acquire an intimate knowledge of the flora without a ten years' acquaintance with plants in the field - or otherwise. But this fact should not deter anyone.
It seems to the author that the following plan of study is essential to a proper knowledge of British plants, though there is no royal road to success, and what applies in one case may not in another.
In the first place, every aspiring systematic botanist should make himself master of a general knowledge of botany. For this purpose he can attend classes or receive help from a special tutor in the subject. Except in a science course, either at school or college, botany is not taught; and the grown-up person who would be a botanist, especially if resident in the country, is somewhat at a disadvantage. For unaided study the only method is to obtain the best textbooks, and to follow out the work gradually, doing as much practical work as possible, and experimenting as often as the call arises.
An elementary textbook may be chosen to begin with, such as Evans's Botany for Beginners. Botany is divided into:
Morphology, the study of form and structure of organs (which includes anatomy, dealing with gross, and histology, dealing with minute structure).
Physiology, dealing with the function of organs and their relation to form and structure; and especially with the activities of the plant, such as nutrition, movement, growth, and reproduction.
Classification (taxonomy, systematic botany), or the study of the relationship of plants, their arrangement or order.
Other branches are Ecology, the study of the habitat of the plant and its life-history; geographical economic botany, diseases of plants, etc.x
As a matter of fact, a special knowledge of morphology is required. Each set of main organs should be carefully studied as root, stem, leaves, flowers, fruit, and seeds, especially the last three. The terms applied to the different types of each should be learnt by means of actual examples or specimens where possible. The relation of one part to the other should be studied, also the order of development, mode of insertion, cohesion, etc.
Floral structure is perhaps the most important, and with this study should be combined some knowlege of the physiology of pollination and fertilization, and in the case of fruits and seeds of maturation, in order properly to understand the form of the flower, and the nature of the ovule and its structure, and development, as also that of the seed. For upon the character of flower, fruit, and seed the most important distinctions applied in classification, whether of orders, genera, or species, are based.
Supplementary to the foregoing, but really part of their subject-matter, is the study of a glossary or the terminology used in botany for the description of parts, whether in general or as applied to special parts. No glossary should be learnt or terminology acquired, however, without comparison between the terms employed and the parts they define in actual specimens if it is possible to obtain them. When the mysteries of botanical terminology have been overcome, an attempt may then be made to describe plants on an approved plan.
1 For more advanced textbooks, see Bibliography.
For this purpose the knowledge already acquired as to the parts of a plant will be of the greatest value. For a description must be framed upon a systematic plan, and the different parts should be described in the order of their development. The main heads should be: Habit, root, stem, leaves, inflorescence, bracts, flowers, calyx, corolla, andrcecium, gynascium, ovules, followed by a floral formula and diagram. (See post.)
The following is an example: Habit. - Erect, perennial, herbaceous, rosette plant
Stem - Aerial stem a scape, leafless.
Radical, in whorl, simple, inversely ovate to spoon-shaped, stalked, fleshy, blunt, midrib broad, no stipules.
In 1-2 series, herbaceous, green, blunt, tipped with black, in an involucre.
Incomplete, perfect; actinomorphic, tubular in disk florets; incomplete, imperfect, zygomorphic; ligulate in ray florets.