LYTHHACE^E, LOOSESTRIFE TRIBE. 219 



CerdtophyUum (Horn-wort), an unimportant family of 

 aquatic plants, very distinct in structure from any 

 other known plants, with rigid whorled leaves, which 

 are repeatedly forked, and inconspicuous flowers. (Name 

 in Greek signifying horn-leaved.) 



1. CERATOPHYLLUM (Horn-wort). 



1. C. demersum (Common Horn- wort). Fruit armed 

 with 2 thorns near the base, and terminated by the 

 curved style. Slow streams and ditches ; frequent. 

 An aquatic plant, growing entirely under water ; with 

 long, slender stems ; whorled, bristle-like leaves, which 

 are 24 times forked, and often inflated and jointed ; 

 the flowers also are whorled, and grow in the axils of 

 the leaves. Fl. July. Perennial. 



* G. submersum scarcely differs from the preceding, 

 except in having fruit without thorns. 



ORD. XXX LYTHKACE^E. LOOSESTRIFE TRIBE. 



Calyx tubular, many-parted, often with intermediate 

 teeth ; petals inserted between the outer divisions of the 

 calyx, soon falling off; stamens springing from the tube 

 of the calyx, within the petals, and either equalling 

 them in number, or twice, thrice, or four times as many ; 

 ovary 2 4 celled ; style single ; capsule many-seeded, 

 covered by the calyx, but not united to it. Herbaceous 

 plants, mostly with opposite leaves, and 4-cornered 

 stems, inhabiting Europe, America, and India. Many 

 of the plants of this tribe possess astringent properties, 

 and some are used for dyeing. The common Purple 

 Loosestrife is found in Australia. Lawsonia inermis 

 is the plant from which the Henna of Egypt is obtained. 

 It is used by the women of that country to stain their 

 nails of an orange colour, and is also employed for dye- 

 ing Morocco leather reddish-yellow. 



1. LYTHRUM (Purple Loosestrife). Calyx cylindrical, 

 with 12 divisions, alternately smaller ; petals 6 ; stamens 



