GROWTH OF PLANTS INDEPENDENTLY OF SEEDS 69 



give about a hundred shoots, reckoning three buds to each " eye." 

 Potatoes do not require as rich soil as many other crops. The 

 best soil for them is a light open soil, well drained, and of a sandy, 

 loamy character. It is interesting to read the directions for 

 planting potatoes which used to be given when they were com- 

 paratively new in England. Thus Evelyn in his Kalendarium 

 Plantarum, the first gardener's calendar published in Britain, 

 writes, " Plant potatoes in your worst ground." In Mortimer's 

 Gardener's Kalendar for 1708 the Potato is thus described : " The 

 root is very near the nature of the Jerusalem Artichoke, although 

 not so good and wholesome but that it may prove good for swine." 

 Gerarde mentions in his Herbale, published 1597, that he culti- 

 vated the plant in his garden, where it succeeded as well as in its 

 native country. This is one of the earliest references to the Potato 

 in England. That potatoes naturally like a sandy soil was 

 observed by Darwin, who relates seeing the wild Potato growing 

 abundantly among the Chomos Islands near the sea beach in 

 thick beds, on a sandy, shelly soil, wherever the trees are not 

 too close together. 



CLASSIFICATION OF SPECIAL FORMS OF STEMS. i. Creeping 

 stems. These sometimes occur above ground, as in the runners 

 of the Strawberry. Rhizomes are generally underground, as in 

 the Bracken, Iris, etc. 



2. Bulbs. These differ from creeping underground stems 

 or rhizomes in having the nourishment contained in the 

 leaves. 



3. Corms, which have a swollen underground stem and very 

 few scale-leaves. 



4. Tubers, which bear " eyes " and are swollen parts of under- 

 ground stems. 



The plant thus has more than one way of storing up nourish- 

 ment. When the plant is propagated by seeds, it is necessary 

 that food for the young seedling should be contained in the seed, 

 or that the seed leaves should be able to make food for it almost 

 as soon as germination begins. If the plant, however, multiplies 

 itself independently of seed, then food must be stored up for it 

 in some other organ, as the root or underground stem. The 



