BOTANY. 



It is either striated with fine parallel lines, 

 or more deeply furrowed ; sometimes it 

 is spotted with a purplish hue. 



The inner part of the stem is either solid, 

 in which case its centre is occupied with 

 pith ; or hollow, and lined with a white 

 shining membrane, of which the hemlock 

 is an example. When the stem is want- 

 ing, a plant is called acaulis, as is the case 

 with the daisy and primrose. The nature 

 of the stem agrees in many respects with 

 the caudex, or body of the root, at least 

 in trees and shrubs ; for such are capable 

 of being propagated by cuttings of their 

 stem or branches, which, when planted, 

 throw out roots. This is not the case, 

 however, with annual stems. Linnaeus 

 calls the stems of trees roots above- 

 ground. It is frequently indifferent which 

 end of a cutting is planted in the earth; 

 and the extremity of a branch bent 

 down to the ground in most cases readily 

 takes root, which circumstances confirm 

 his idea. 



The stem of several plants is subject to 

 a disease, whence it becomes as it were 

 compound or clustered, forming a broad 

 flat figure, crowded with leaves or flow- 

 ers at the extremity, and sometimes be- 

 sprinkled with them at the sides. We 

 have seen it in the ash, holly, broom, 

 nasturtium, wall-flower, toad-flax, &c. A 

 kind of pea is frequently cultivated in 

 Norfolk with red and white flowers, and 

 a tender eatable pod, called the top-knot 



Eea, in which this variety of stem is regu- 

 irly propagated by seed. 



2. Culmus, a straw, or culm, fig. 10, is 

 the peculiar stem of grasses, rushes, and 

 such like plants. It bears both leaves and 

 flowers, and in that respect comes under 

 the denomination of a caulis; but is readily 

 known by its habit, though difficulties at- 

 tend its definition. In most grasses, corn, 

 &c. it is jointed in a manner peculiar to it- 

 self, and then cannot be mistaken ; but in 

 common rushes, and some few grasses, it 

 is destitute of joints. When these parts 

 are bent, it is called geniculute, and such 

 joints readily take rooU 



3. Scapus, a stalk, fig. 11, springs im- 

 mediately from the root, bearing flowers 

 and fruit, but not leaves, as in the prim- 

 rose and cowslip. It is either simple or 

 branched, naked or scaly. In the cycla- 

 men it becomes spiral after flowering, and 

 buries the seeds in the ground. Dr. 

 Smith has found, contrary to the opinion 

 of Linnaeus, that a plant may sometimes 

 be increased by its scapus, as in lachena- 

 lia tricolor, which occasionally bears bulbs 

 on its stalk. 



4. Peduncitlus, the flower-stalk, fig. 12. 



.,'* J. GU,(&/t\,l 



springs from the stem or branches, b em- 

 ing flowers and fruit, but not \CA\ es. Pe- 

 dicellus is a partial flower-stalk, or, in other 

 words, the ultimate subdivision of a gene- 

 ral one. The most common situation of 

 a flower-stalk is axillary, originating from 

 between a leaf and the stem, or between 

 a branch and the latter. It is rarely op- 

 posite to a leaf, as in some species of 

 geranium, and still more rarely interme- 

 diate between two leaves, as in some 

 kinds of solanum. It is either terminal or 

 lateral ; solitary, clustered, or scattered ; 

 simple or branched. According to the 

 various modes in which it is subdivided, 

 several kinds of inflorescence are distin- 

 guished, to be mentioned hereafter. Ses- 

 sile flowers are such as have no stalk. 

 The flower-stalk is occasionally naked, or 

 furnished with bracteas. Very rarely it 

 bears tendrils. 



5. Petiolus, the foot-stalk, fig. 13, is ap- 

 plied exclusively to the stalk of a leaf, 

 and is either simple, as in all simple 

 leaves, or compound, as in the greater 

 part of compound ones. Sometimes it 

 bears tendrils. It is generally channelled 

 on the upper side, and more or less di- 

 lated at the base ; in one or two instances 

 the flower-stalk grows out of it, as in tur- 

 nera. Leaves that have no foot stalk 

 whatever are called sessile. The sap-ves- 

 sels are for the most part very conspicu- 

 ous in foot-stalks, and their spiral coats 

 are easily observed. 



5. From, a frond. This term, which 

 properly means a bough, is technically 

 applied by Linnaeus to express the stem, 

 leaf, and fructification being united, that 

 is, the leaf bears the flowers and fruit. 

 The term is only used in the class Cryp- 

 togamia. Ferns which bear seeds on the 

 back of their leaf are genuine instances' 

 of this, and it is applied to lichens, &c. 

 Plate II. fig. 14. 



7. Stipes, stipe, is the stem of a frond, 

 fig. 15, or the stalk of a fungus, as in the 

 common eatable mushroom. In the for- 

 mer instance it is very generally clothed 

 with scales of a peculiar chaffy texture ; 

 in the latter it is very often invested by 

 a ring, formed of the membrane which 

 had previously covered their fructifica- 

 tion. 



OF THE LEAVES. 



The leaf, folium, fig. 16 and 17, is a very 

 general organ of vegetables, yet not 

 absolutely necessary to all plants, for the 

 stems and stalks occasionally perform its 

 functions. What those functions are we 

 shall in a compendious manner explain 



