Book I. 



ANOMALIES OF VEGETABLE DEVELOPEMENT. 



245 



1560. The root. According to the general laws of vegetable developement, plants of 

 the same species are furnished with the same species of root not producing at one time 

 a woody or fibrous root, and at another time a bulbous root. And yet it is found that 

 there are cases in which changes of this kind do occur. If part of the root of a tree 

 planted by a pond or river, protrudes beyond the bank so as to be 

 partially immersed, it divides at the extremity into innumerable 

 ramifications, or sends out innumerable fibres from the surface, 

 which become again subdivided into fibres still more minute, and 

 give to the whole an appearance something resembling that of the 

 tail of a fox ; which has accordingly been denominated by Du 

 Hamel the fox-tail-root. (Jig. 231.) 



1561. The root of the Phlcum pratcnse, when growing in a moist soil, which 

 it naturally afFects, is uniformly fibrous ; but when growing in a dry soil, where 

 it is also often to be found, it is furnished with a bulbous root. The same is 

 the case with the alopecurus geniculatus ; which, when growing in its native 

 marshes, protrudes a fibrous root, though, when growing in a very dry situation, 

 as on the top of a dry wall, it is found to be furnished with an ovate and juicy 

 bulb. This anomaly also seems to be merely the result of a provision of nature 

 l^ which the plant is endowed with the capacity of collecting a supply of ^ 

 moisture suited to existing circumstances, and hence of adapting itself to the; 

 soil in which it grows. , 



1562. The roots of Utricularla minor, which consist of a number of slender t 

 and hair-hke filaments, exhibit the singular anomaly of being furnished with a 

 multitude of small and membraneous bladders, each containing a transparent 

 and watery fluid, and a small bubble of air, by means of which the plant is kept floating in the water. 



1563. The descending root, an anomaly which attends some perennials, is at first spindle-shapetl and per- 

 pendicular, sending out some lateral fibres : but dying at the lower extremity in the course of the succeed- 

 ing winter, and protruding new fibres from the remaining portion, and even from the lower portion of the 

 stem, in the course of the following spring, which by descending into the soil, draw down the plant with 

 them, so that part of what was formerly stem is now converted into root. This process is repeated every 

 year, and by consequence a portion of the stem is made to descend every year into the earth. The 

 anomaly may be exemplified in the roots of Valeriana dioioa, tanacetum vulgare, and oxalis acetosella ; 

 and will also account for the bitten and truncated appearance of scabiosa succisa, or devil's-bit. 



1564. The beet-root, if dissected when about a year old, presents the singular anomaly of being already 

 furnished with from five to eight distinct and concentric circles of longitudinal tubes or sap-vessels, im- 

 bedded at regular intervals in its pulp ; whereas other biennial roots form only an individual circle each 

 year, and are, consequently, at no time furnished with more than two. 



1565. Migratory roots depend on a principle similar to the foregoing. If the stem of a descending root 

 happens to be creeping or procumbent instead of being erect, then the lateral shoots from above are carried 

 forward in the direction of that procumbency, so that in the course of a few years the plant has actually 

 changed its place by so much as the stem has been converted into a root. This is well exemplified in the 

 genus Jris, which, as it enlarges in circumference, dies in the centre and presents a ring of plants instead 

 of a solitary one. In the case of some aquatics, which float about on the surface of the water as they hap- 

 pen to be driven by the winds, the whole plant may be said to be migratory, as in the case of the genus 

 Lemna, and some marine plants. 



_ 1566. Roots changed to branches and branches to roots. If the stem of a young plum or cherry tree, but 

 particularly of a willow, is taken in the autumn and bent so as that one half of the top may be laid in the 

 earth, one half of the root being at the same time taken carefully out, but sheltered at first from the cold 

 and then gradually exposed to it, and the remaining part of the top and root subjected to the same process 

 in the following year, the branches of the top will become roots, and the ramifications of the root will 

 become branches, protruding leaves, flowers, and fruit in due season. 



1567. If the stem of a tree planted by a pond or river is so bent in its growth as to 

 come near to the surface of the water and to be occasionally immersed in it, it will 

 sometimes send out from the under surface a multitude of shoots that will descend into 

 the water, and develope themselves in the manner of the fox-tail-root. Sometimes it 

 happens that a stem, instead of assuming the cylindrical form common to the species, 

 assumes a compressed and flattened form similar to the herbage of the cactus as in the 

 fir-tribe, ash, &c. 



1568. The anomaly of the flattened stem {fig. 232.) is accounted for by Du 

 Hamel by supjjosing that an unnatural graft must have taken place in the 

 leaf-bud; and so united shoots that would otherwise have been distinct. 

 Sometimes the stem is disfigured by accidental tumors or bunches projecting 

 from the surface, and forming ultimately what are called knots in the wood. 

 They are very common in the oak and elm, and are produced perhaps by 

 means of some obstruction in the channel of the sap's motion, by which the 

 vessels become convoluted and swell up into a bunch. 



1569. But bunches are also to be met with on the stem of herbaceous plants, 

 as on that of the carduus pratensis ; of which you will often find a portion 

 near the top swollen out into an egg-shaped or egg-oblong bunch, extending 

 from an inch to two inches in length, and about an inch across. If this 

 bunch is cut open in the month of August, it will be found to contain several 

 large and white maggots. It has consequently been occasioned by the 

 imncture of the parent insect depositing its eggs. It does not seem to affect 

 the general health of a vigorous plant, though it might prove seriously in. 

 jurious to a weak one. 



1570. Bundled ste?n. Sometimes two or more contiguous stems, extending 

 in the process of their growth till they meet and press against one another, 

 become incorporated at length into one, and form a sort of bundle. This is 

 what may be termed a natural graft, in opposition to an artificial graft, of 

 which it is the model and prototype. The natural graft is always effected 

 by means of the union of the liber of the respective stems composing it ; so 

 that the perfection of the art of grafting consists in applying the liber of the 

 graft and stock together in such a manner as shall most facilitate their 

 jMcorporation. . 



