THE liULB BOOK 



It should be noted that while all true bulbs and corms are 

 confined to the Monocotyledons, tuberous plants have a much wider 

 range. They are to be found not only amongst Monocotyledons, but 

 also amongst the other great group of flowering plants known as 

 Dicotyledons. These are generally recognised 

 by having (1) net-veined leaves; (2) parts of 

 the flower {i.e., the sepals, petals, stamens, 

 carpels) in four's or five's, or multiples of 

 them ; (3) and when raised from seed, by 

 having two seed-leaves. An apparent con- 



Fio. 10. — Seedling Cyclamen, showing aberration 

 Fig. ^.—hichardia cethiopica. (J.) from ordinary dicotyledonous type. 



tradiction to this arrangement is seen in the seedlings of Cyclamen, 

 as shown in the sketch (Fig. 10). When the seeds first germinate, 

 only one seed-leaf is apparent ; later, a second one much smaller than 

 the first appears, and with advance in age one leaf succeeds another 

 rapidly until the top of the tuber is furnished with a good supply. 



RHIZOMES. — A rhizome is a shoot or stem that grows more or 

 less horizontally, and usually beneath the surface of the soil. Many 

 plants have rhizomes, some thickened and somewhat tuberous, 

 others slender. Good examples of plants with thick rhizomes are 

 the German and Florentine Irises or "Flags" (Fig. 11), and Solomon's 

 Seal (Fig. 12); while the Lily of the Valley (see Fig. 99, p. 149) 

 may be taken as an example of a plant with slender rhizomes. 



In tiie Tritonia or Montbrotia (Fig. 13) we have an example of 

 plant in which both corms and rhizomes are developed. It will be 

 seen from the sketch that the corms are not actually placed upon 

 each other as in the Crocus and Gladiolus, but are separated by a 

 kind of runner-like rhizome, some joints of which swell into a conn 

 if sufficient nourishment has been elaborated by the leaves. 



