194 



MANUAL OF POISONOUS PLANTS 



anther idium ; the ^g cell is contained in a spirally coiled oogonium and after 

 fertilization becomes an oospore. The Stoneworts or Charas are common i: 

 brackish water, and though not injurious frequently stop up canals and fill pond- 

 so that it becomes necessary- to pull them out. 



PHAEOPHYCEAE 



Brown algae : chloroiAyll marked by a brown coloring matter, phycophaev. 

 reproduction sexual and asexual, swarm spores, sperm cells and egg cells ; 

 marine : tetragonidia absent. 



The Phaeosporeae contain the Laminariaceae : the Devil's Apron, Laminana 

 digitata, and other species from which iodine and mannite are derived. The 

 Macrocysfis pyrifera is of great length. The Clyclosporeae contain the family 

 Fucaceae, the common Bladderwrack i^Ftuus vesiculosus) from which iodine. 

 bromine and soda are obtained. The Sargasso weed {Sargassum hacciferum 

 found in the Atlantic ocean is also abundant in the Sargasso Sea. 



DICTYOTALES 



Brown algae ; reproductive bodies without motion ; tetragonidia present 

 This group contains a single order Dictj-otaceae comprising a few genera. 



RHODOPHYCEAE 



Red or violet algae; chromatophores contain chlorophyll and red coloring 

 matter (phycoer>-thrin and rhodoph}ll) ; reproduction sexual and asexual; most- 

 ly marine. The red sea weeds are divided into several classes and numerous 

 orders. The sub-class Florideae contains most of the species. Food is ob- 

 tained from several species and the carrageen is furnished by Chondrus cris- 

 pus, agar agar is obtained from Gracihria lichenoides found in the Indian 

 Ocean. The Gloiopeliis coliformis and other species are used by the Japanese 

 as food. Many of the species are prettj- and are much gathered on the sea coast 



Fig. .'". i>-- 5c* Weed, Semclion multsAdum. 1. Branch with carpogonium and 

 antheridium. 2-4. Different stages of development. S. Lejoliria medilerranfa with antheridi- 

 nm, carpogonium and spores, a — antheridia. c and o — carpogonia, t — trichogyne, s — spena 

 cells, e — spores, f — fruit, .\fter Thuret and Bomet. 



