194 



MANUAL OF POISONOUS PLANTS 



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

 fertilization becomes an oospore. The Stoneworts or Charas are common in 

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

 so that it becomes necessary to pull them out. 



PHAEOPHYCEAE 



Brown algae ; chlorophyll marked by a brown coloring matter, phycophaein, 

 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 

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

 Fucaceae, the common Bladder wrack {Pucus vesiculosus) from which iodine, 

 bromine and soda are obtained. The Sargasso weed {Sargassum bacciferum) 

 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 Dictyotaceae comprising a few genera. 



RHODOPHYCEAE 



Red or violet algae; chromatophores contain chlorophyll and red coloring 

 matter (phycoerythrin and rhodophyll) ; reproduction Sexual and asexual ; most- 

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

 orders. The sub-class Plorideae 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 Gracilaria lichenoides found in the Indian 

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

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



Fig. 37. Red Sea Weed, Nemalion multHidum. 1. Branch with carpogonium and 

 antheridium. 2-4. Different stages of development. S. Lejolisia mediterranea with antheridi- 

 um, carpogonium and spores, a — antherxdia, c and o — carpogonia, * — trichogyne, i — sperm 

 cells, e — spores, f — fruit. After Thuret and Bornet. 



