U02 



JOURNAL OF THE KOYAL HORTICULTURAL SOCIETY. 



ROOTS AND THEIR USES. 

 By Rev. Prof. G. Henslow, M.A., V.M.H., &c. 



[Lecture to the Students at the Society's Gardens, June 18, 1902.] 



Germination. — When a Mustard-seed germinates, the first visible 

 result is the protrusion of the radicle. This is not the root, but forms 

 the primary stem, called the " hypocotyl," * carrying the two green, 

 edible cotyledons at the top. The undeveloped bud, or plumule, lies 

 between them. These three parts constitute the entire embryo. 



The root is formed by the " growing point " at the extremity of the 

 radicle, just below the actual tip, and (with rare exceptions) grows down- 

 wards, penetrating the soil, vertically. This latter direction is regarded 

 as being due to the influence of gravity ; for if a germinating seed be 

 supported horizontally, the root soon begins to turn downwards again. 

 It also " circumnutates," or " bows around." This possibly aids the tip 

 in finding a line of least resistance to penetration. 



Primary Root. — The primary or axial root may elongate very con- 

 siderably, as of the long- rooted Radish, Carrot, Parsnip, kc. If the plant 

 be an annual, this root does not acquire any great size ; but in a biennial 

 the leaves have had a longer period of activity, so that there is more 

 starch, &C., made by them than can be utilized, and the root has to be 

 enlarged in order to store up this increased amount of reserve food- 

 materials. 



Garden Carrots were thus made, by sowing the seed of the wild 

 annual Carrot (Daucus Carota) late in the season. This prevented the 

 plants from flowering the same year. They thus had a season and a 

 half for vegetative growth. Then, by selecting the latest flowering for a 

 few years, the existing biennial races were established. 



A converse effect was made with Beetroot (Beta vulgaris, var. 

 muritima), for this is a common perennial on our sea-coast cliffs. By 

 treating the seeds in the same way, the perennial habit was lost and the 

 biennial races of Beets and Mangolds were obtained. 



Root FORMS. — Since the garden root-crops have been raised from 

 wild plants the forms have changed considerably. Thus, while the root 

 of the wild Carrot, Parsnip, Turnip, and Radish is long and wiry, we 

 have in cultivation all sorts of ''longs and shorts," cylindrical and globe 

 forms, &c. ; and the question arises — how did they come about ? 



Pliny, writing in the first century, says that the Greeks in his day had 

 discovered a way of converting the female t " rape into a male " — that is, 

 the long-rooted into the short form — by sowing the seed in a cloggy soil. 



M. Carriere experimented with the wild Radish (linphanus Raplian- 

 istrum) and found that he got a larger percentage of long roots in a loose 



* I.e. " under the cotyledons." 



f The terms " male " and " female " were often used then, as also in the Middle 

 A^es, but only in a fanciful way. 



