OUTLINES OF BOTANY. lv 



and Floras. Luxuriance entails not only an increase in the size of the 

 whole plant, or of particular parts, but often also an increase of number in 

 branches, in leaves, or leaflets of a compound leaf; or it may diminish 

 the hairiness of the plant, induce thorns to grow out into branches, etc. 



Capsules which, while growing, lie close upon the ground, will often be- 

 come larger, more succulent, and less readily dehiscent, than those which 

 are not so exposed to the moisture of the soil. 



Herbs eaten down by sheep or cattle, or crushed underfoot, or other 

 wise checked in their growth, or trees or shrubs cut down to the ground, 

 if then exposed to favourable circumstances of soil and climate, will send 

 up luxuriant side-shoots, often so different in the form of their leaves, in 

 their ramification and inflorescence, as to be scarcely recognisable for the 

 same species. 



Annuals which have germinated in spring, and flowered without check, 

 will often be very different in aspect from individuals of the same spe- 

 cies, which, having germinated later, are stopped by summer droughts or 

 the approach of winter, and only flower the following season upon a se- 

 cond growth. The latter have often been mistaken for perennials. 



Hybrids, or crosses between two distinct species, come under the same 

 category of anomalous specimens from a known cause. Frequent as they 

 are in gardens, where they are artificially produced, they are probably 

 rare in nature, although on this subject there is much diversity of opinion, 

 some believing them to be very frequent, others almost denying their ex- 

 istence. Absolute proof of the origin of a plant found wild, is of course 

 impossible ; but it is pretty generally agreed that the following particulars 

 must always co-exist in a wild hybrid. It partakes of the characters of its 

 two parents ; it is to be found isolated, or almost isolated, in places where 

 the two parents are abundant ; if there are two or three, they will generally 

 be dissimilar from each other, one partaking more of one parent, another 

 of the other ; it seldom ripens good seed ; it will never be found where one 

 of the parents grows alone. 



Where two supposed species grow together, intermixed with numerous 

 intermediates bearing good seed, and passing more or less gradually from 

 the one to the other, it may generally be concluded that the whole are mere 

 varieties of one species. The beginner, however, must be very cautious not 

 to set down a specimen as intermediate between two species, because it ap- 

 pears to be so in some, even the most striking characters, such as stature 

 and foliage. Extreme varieties of one species are connected together by 

 transitions in all their characters, but these transitions are not all observable 

 in the same specimens. The observation of a single intermediate is there- 

 fore of little value, unless it be one link in a long series of intermediate forms, 

 and, when met with, should lead to the search for the other connecting links. 



(2) Accidental aberrations from the ordinary type, that is, those of which 

 the cause is unknown. 



These require the more attention, as they may sometimes lead the begin- 

 ner far astray in his search for the genus, whilst the aberrations above-men- 

 tioned as reducible more or less to general laws, affect chiefly the distinction 

 of species. 



Almost all species with coloured flowers are liable to occur occasionally 

 with them all white. 



Many may be found even in a w T ild state with double flowers, that is, with 

 a multiplication of petals. 



