Classification of Plants 243 



The order Gnetaceae is represented by Gneium and Wel- 

 wltschia. Welwitschia is well adapted for its life in the Dama- 

 raland desert, to which it lends an additional weirdness. The 

 trunk is very short, sometimes two or three feet thick, and grows 

 mostly under the soil. The large tap-root extends deep down 

 in the sand. It has but two leaves besides the cotyledons six 

 feet or more in length, which become split into narrow shreds 

 as they are lashed by the wind. Like other leaves found in 

 deserts, they have a very thick cuticle. The large two-lobed 

 summit of the trunk bears the crimson cones. The fruiting 

 cones are about 2 inches long. 



The staminate flowers have a four-parted perianth and six 

 stamens surrounding a reduced ovule. The pistillate flower has 

 a tubular perianth and contains an exposed ovule. 



Division V. — Angiosperms. 



Sub-class I. — Monocotyledons. 



Order Typhace^. 



This order which contains the single genus Typha (Cat's 

 tail Bulrush) is placed, in the Engler system, among the most 

 primitive of the Monocotyledons. The erect stem arises from 

 a thick rhizome and bears a dense velvety inflorescence of 

 pistillate flowers with staminate flowers above. Each flower 

 is surrounded with a number of hairs. Stamens 2-5 ; carpels 

 with one pendulous ovule. Fruit an achene covered with 

 hairs which aid in its distribution. The flowers are wind pol- 

 linated. 



The incomplete and imperfect flowers, the single genus and 

 the few species (12) attest to the ancient lineage of this order. 

 It is found in fossil form in Tertiary times. Fossils of di- 

 cotyledons are, however, found before this. 



Order Cyperace/e, the Sedges or Nut Grass Family. 



This family consists of tufted wiry grass-like plants with 

 creeping grass- like sympodial rhizomes. Stem 3-angled and 



16* 



