BOTANY. 



BOTANY. 



with the power of rejecting what is hurtful, 

 and selecting what is beneficial to its parent 

 plant, from any mixed solution of substances 

 not corrosive or poisonous. 

 Botanists distinguish seven kinds of roots. 



1. The fibrous root (radix Jibrosd], consist- 

 ing of fibres alone, either branched or undi- 

 vided, as that of the Foa annua, that species 

 of grass so troublesome in gravel walks, &c. 



2. The creeping root (R. repens). This 

 spreads and branches horizontally, throwing 

 out fibres in its course, as some kinds of mint 

 (Mentha), and the couch-grass, or twitch (Tri- 

 ticum repens). 



3. Tapering root (R.fusiformis), as that of 

 the carrot, &c. 



4. Abrupt root (12. praemorsd), appears in- 

 clined to be a tapering one, but, from some 

 natural decay or habit, becomes abrupt, or ap- 

 parently bitten off, as in the devil's-bit sca- 

 bious (Scabiosa succisa), and several of the 

 hawk-weeds. 



5. Tuberous root (R. tuberosa), consists of 

 fleshy tubers connected by fibres, as in the po- 

 tato (Solarium tuberosum). It is the premature 

 formation of the tubers which prevents the 

 blooming of the Jerusalem artichoke, and some 

 of the early varieties of the potato. If the tu- 

 bers are removed as soon as they are formed, 

 the plants blossom. 



6. Bulbous root (R. bulbosa), is solid, as in 

 the crocus ; tunicate, composed of concentric 

 layers, as in the Onion (AUium cepa)\ or 

 scaly, as in the lilies. 



7. Jointed or granulated root (R. articulata 

 or granulata), is a cluster of either little bulbs 

 or scales, connected by a common fibre, as in 

 the wood-sorrel (Oxalis acetosella), and white 

 saxifrage (Saxifraga granulata). 



The roots of plants sometimes change their 

 form with the situation in which they grow. 

 Those of some grasses are bulbous in a dry 

 situation, and fibrous in a moist one. Thus 

 we see the care of Providence is manifested 

 even in providing for the welfare of a weed ; 

 bulbous roots being, as it were, reservoirs of 

 moisture, enable such plants to perfect their 

 seed in the driest season. Again, the fibrous 

 roots of grasses growing in sandy sterile places 

 are remarkably downy; by this means they re- 

 tain firmly their hold in so yielding a medium, 

 and their absorbing surfaces are likewise in- 

 creased, not unnecessarily, where nourishment 

 is so scanty. 



Seven kinds of stalks or stems are distin- 

 guished by botanists; 1. A stem (caulis) is 

 confined to such as bear both leaves and 

 flowers, which is the case with the trunks of 

 all trees. It is either simple, as in the white 

 lily, or branched, as in most cases. In gene- 

 ral it grows upright, but sometimes it is more 

 or less recumbent. Some cling to other bodie? 

 by fibres for support, as the ivy (Hedera helix) 

 or by tendrils, as the vine. Others twine round 

 such plants as come in their way. A remark- 

 able distinction is to be observed in twining 

 plants. Honeysuckles, &c., twine from left to 

 right ; whilst others, as the kidney-bean, twine 

 from right to left, nor can any art induce them 

 to alter their course. Some trail along the 

 ground; some are jointed, as in the samphire 

 27 



and Indian fig. They are of various forms, 

 round, three-sided, square, &c. Their surfaces 

 are smooth, viscid, rough, bristly, hairy, &c. 

 [nternally they are solid or hollow. Plants 

 without stems are termed acaules. 



2. A culm or straw (culmus), is only a va- 

 riety of the caulis, but, being peculiar to the 

 grasses, rushes, and other plants nearly allied 

 to them, has been deemed worthy of a separate 

 name. It is without joints, as in the common 

 rushes ; jointed, as in wheat, &c. ; bent like a 

 knee, as in Alopecurus geniculatus. It varies 

 in being hollow, solid, hairy, &c. 



3. A stalk (scapus), springing from the root, 

 bears only flowers and fruit, as that of the 

 primrose (Primula vulgaris), and cowslip (P. 

 veris). In the first it is simple, in the latter 

 subdivided and many-flowered. It is some- 

 times scaly ; in which case the scales are apt 

 to sport into leaves, and thus render it a proper 

 caulis. It greatly varies as to length, manner 

 of growth, &c. 



4. A flower stalk (pedunculus), springing 

 from the stem, bears only fruit and flowers. A 

 partial flower stalk (pedicetlis), is the ultimate 

 division of a general one, as in the cowslip be- 

 fore instanced. Flowers without stalks are 

 termed sessile, as the dodders, &c. 



5. The leaf stalk (petiolus), signifies the 

 stalk of a leaf only. It is solitary or simple, 

 as in the lilac, and all other simple leaves. It 

 is common in the rose, &c. It is usually chan- 

 nelled on its upper side. 



6. A frond (frons), is now used only in de- 

 scribing the class Cryptogamia, and signifies a 

 leaf which produces both flowers and fruit, as 

 in the ferns, lichens, &c. 



7. A stipe (stipes), is the stem of a frond. 



It will be better to defer the consideration 

 of the functions of roots and stems until we 

 take a connected view of the phenomena of 

 vegetable life. 



Leaves are a very general, but not a uni- 

 versal part of the vegetable body; they ars 

 wanting in the samphires, creeping cereus, 

 &c. Such plants are called plantaeaphyllx 

 (leafless plants). The situations, forms, in- 

 sertions, and surfaces of leaves are of great 

 use in botanic descriptions; a few must at 

 present suffice : 



Folia radiculia spring from the root, as in the 



primrose. 

 Folia caulina and ramea spring respectively 



from the stem or branch. 

 Folia bina terna, &c., leaves in pairs, or three 



together, &c. 

 Folia verticillata, whorled, several opposite, or 



growing in a circle round the stem. 

 Folia peltata, peltate, having the foot-stalk in 



the centre, as the nasturtium. 

 Folia sessilia, sessile, having no foot-stalk. 

 Folia perfuliata, perfoliate, when the stem runs 



through their centre. 



Leaves are nearly circular, roundish, egg- 

 shaped or ovate, oblong, lanceolate, &c.; they 

 terminate abruptly, or are sharp, jagged, point- 

 ed, cirrhose (. e. tipped with a tendril), &c. 

 Their margins are entire, spinous, toothed, 

 wavy, &c. Their surfaces are dotted, rugged, 

 veiny, coloured (i. e. tinted with any colour 

 s 2 209 



