468 



EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



leaves alternate, entire, with somewhat sheathing petioles ; the 

 flowers perfect, in racemes or spikes, destitute of all floral envel- 

 opes. Stamens definite. Ovary composed of three to five, more 

 or less united, few-ovuled carpels, with distinct styles or stigmas. 

 Capsule or berry with usually a single seed in each cell. Embryo 

 heart-shaped, minute, inclosed in the persistent embryo-sac, at the 

 apex of the albumen ! Ex. Saururus (LizardVtail). Slightly 

 pungent plants. They are scarcely distinct from the Pepper 

 Family.* 



872. Ord, Ceratophyllacese (the Hornwort Family), consists of the 

 single genus Ceratophyllum (growing in ponds and streams in 

 many parts of the world) ; distinguished by the whorled and dis- 

 sected leaves with filiform segments ; the flowers monoecious, and 

 sessile in the axil of the leaves ; the stamens indefinite, with sessile 

 anthers ; and the simple one-celled ovary, which forms a beaked 

 achenium in fruit, containing an orthotropous suspended seed, with 

 four cotyledons ! and a manifest plumule. 



873. Ord, Callitrichaceae (the Water- Starwort Family), formed of 



* ORD. PIPERACE^E (the Pepper Family), a chiefly tropical order with 

 the embryo inclosed in the persistent embryo-sac, differing from Saururaceae 

 principally in the one-celled simple ovary, with a solitary ovule (fruit a berry), 

 and the extrorse anthers; the leaves often opposite or whorled; the jointed 



FIG. 1029. Cair.triche verna, about the natural size. 1030. Perfect flowers, magnified. 

 1031. A staminate and a pistillate flower, magnified. 1032. The fruit. 1033. Cross-section of 

 the fruit. 1034. Vertical section through the pericarp, seeds, and embryo. 



