2020 A TEXTBOOK OF THEORETICAL BOTANY 



banks in many parts of the world, including Britain. The lower part of the 

 stem is a thick rhizome while the upper part projects high above the water 

 and bears a dense spike divided into two parts. The lower, which is brown 

 in colour, consists of female flowers, while the upper, which is yellow, 

 consists of male flowers. Pollination is by wind. The fruit, which is an 

 akene, is covered by long downy hairs and is wind-distributed. 



The Sparganiaceae also contain only a single genus, Sparganium, 

 with eighteen species living in temperate and colder parts of the northern 

 hemisphere. One species is found in New Zealand. They are aquatic, or 

 marsh-inhabiting herbs, with a creeping, perennial rhizome bearing erect 

 or floating shoots and distichously arranged narrow, entire leaves, sheathing 

 at the base. The flowers are formed in spherical heads, the males usually 

 being produced higher up than the females. The flowers are protogynous 

 and pollination is anemophilous. Five species, including S. erectuw, S. 

 simplex (Fig. 1957) and S. minimum occur in Britain and are known collec- 

 tively as the Bur-reeds. The first two are widely distributed from the 

 Arctic Circle to North Africa and from the Himalayas eastwards to Japan. 



AMARYLLIDALES 



The Amaryllidales are monocotyledonous herbs with a tunicated bulb 

 or very rarely a rhizome. The leaves are radical and usually linear. The 

 flowers are usually borne in umbellate inflorescences or rarely solitary on 

 a leafless scape and are subtended by an involucre of one or more mem- 

 branous bracts. There are usually six stamens. The ovary may be 

 superior or inferior and is generally trilocular, bearing numerous ovules 

 with axile placentation. The fruit is either a capsule or a berry. 



There is only a single family Amaryllidaceae. 



The above description is taken from Hutchinson and represents his 

 new conception of the family, in which the form of the inflorescence rather 

 than the position of the ovary is regarded as the distinguishing feature. 

 The result of this change is, as we have seen, that several sections of the old 

 Liliaceae can now be transferred to the Amaryllidaceae. The most 

 important of these are the Agapantheae and the Allieae. The Agapantheae 

 are regarded as the most primitive group and link the family to the Liliaceae. 

 The Allieae stand as an intermediate group between the Agapantheae and 

 the Amaryllideae. 



Though this view of the limits of the Amaryllidaceae is not universally 

 accepted there appears to be so much in favour of Hutchinson's view that 

 we have here followed his suggestions. 



Amaryllidaceae 



The Amaryllidaceae are a relatively small family which includes a num- 

 ber of common wild and garden plants. Most of them perennate by bulbs 

 and very rarely by a rhizome, though the latter occurs in those genera which 

 may be regarded as more primitive. 



