2000 



A TEXTBOOK OF THEORETICAL BOTANY 



II, 



means of the leaves whose tips twine Hke tendrils. The flowers 

 are pendulous. Several species are cultivated in greenhouses. 

 Littonia with four species occurs in South and Central Africa 

 and has a habit similar to Gloriosa. 

 Veratreae. Rootstock a short erect rhizome or bulb, stem leafy or 

 leaves sub-radical. Inflorescence a raceme, panicle or spike. 

 Perianth segments unequal, free. Stamens six, attached at the 

 base of the perianth segments. Fruit a septicidal capsule. Seeds 

 narrow or winged. 

 The only genus is Veratrum with fifty species in north temperate 

 regions. The rhizome bears a tall leafy stem and racemes, the 

 lower flowers of which are hermaphrodite, while the upper are 

 usually male, caused by abortion of the gynoecium. Some plants 

 are found bearing only male flowers. They are pollinated mainly 

 by flies, nectar being exposed at the thickened base of the perianth 

 segments. V. album, which is common in central and southern 



Europe, is the source of a drug which 

 is sold under the name of White 

 Helleborine Root. V. nigrum which 

 is also used medicinally is called 

 Green Helleborine. 

 12. Asparageae. Rootstock a rhizome. Stem 

 erect or climbing, sometimes woody. 

 Leaves reduced to scales bearing in 

 their axils small, linear cladodes. 

 Flowers hermaphrodite, pedicels 

 articulated near the top (see p. 1 142). 

 Perianth segments free. Stamens 

 six, hypogynous and free. Fruit 

 a globose berry, seeds few or 

 solitary. 

 There is only one genus. Asparagus, 

 which is distributed through tem- 

 perate and tropical regions of the 

 Old World but is absent from 

 America. The genus contains about 

 300 species, mostly xerophytes. A. 

 officinalis (Fig. 1935) occurs rarely 

 in Britain near the sea. The plant is 

 cultivated and the young shoots 

 eaten as a vegetable. 



Fig. 1935. — Asparagus officinalis. 

 Garden Asparagus. Shoot 

 with male flowers. The 

 leaves are replaced by small, 

 needle-like cladodes. 



I 



II. Rootstock a bulb or a corm 



I. Tulipeae. Rootstock a bulb. Stem bearing one or more leaves. 

 Flowers solitary or in a racemose umbellate inflorescence. 

 Perianth segments free, stamens six. Fruit a capsule splitting 



