ZOSTERACEAE. 



Family 2. ZOSTERACEAE Dumort. 



Eel-grass Family. 



Perennial marine herbs, with long rootstocks and branching stems. 

 Leaves alternate linear, sheathing. Flowers monoecious or dioecious, borne 

 on a 1-sided spadix enclosed in a spathe. Staminate flowers of a sessile 

 1-celled anther. Pistillate flowers of 2 united carpels, a distinct style and 

 2 filiform stigTtias. Two genera and seven or eight species, inhabiting 

 the ocean. 



1. ZOSTERA L. 



Marine plants with slender rootstocks and compressed stems. Leaves 2- 

 ranked, the sheaths with infiexed margins. Spadix linear. Flowers monoecious, 

 arranged alternately in 2 rows on the spadix. Staminate flower atached to the 

 spadix near its apex, the anther opening irregularly on the ventral side ; poflen 

 thread-like. Pistillate flower fixed on its back near the middle ; ovary 1 ; style 

 elongated; mature carpels fiask-shaped, membranous, rupturing irregularly, 

 beaked by the persistent style; seeds ribbed; embryo ellipsoid. [Greek, refer- 

 ring to the ribbon-like leaves.] About 6 species of marine distribution, the fol- 

 lowing typical. 



1. Zostera marina L. Eel- 

 grass. Grass-wrack. (Fig. 3.) 

 Leaves ribbon-like, obtuse at the 

 apex, l°-6° long, about 3" wide, 

 with 3-7 principal nerves. Spa- 

 dix l'-4' long; flowers crowded, 

 usually from 10-20 of each kind 

 on the spadix; ovary somewhat 

 vermiform; at anthesis the stig- 

 mas are thrust through the open- 

 ing of the spathe and drop off 

 before the anthers of the same 

 spadix open; the anthers at an- 

 thesis work themselves out of the 

 spathe and discharge the glutin- 

 ous stringy pollen into the water ; 

 seeds cylindric, strongly about 20- 

 ribbed, about 1*" long, truncate 

 at both ends, the ribs showing 

 very clearly on the pericarp. 



In the ocean, washed ashore. 

 Native. Of very wide marine dis- 

 tribution from GreenLand to Florida, from Alaska to California and on the coasts 

 of the Old World. 



Family 3. CYMODOCEACEAE Kerner. 



Manatee-grass Family. 



Submerged marine perennial herbs with long rootstocks. Leaves 

 narrow, sheathing. Flowers monoecious or dioecious, solitary or eymose. 

 Staminate flowers of two long-pedicelled anthers, the anthers 2-celled, 

 longitudinally dehiscent. Pistillate flowers of 1 or 2 carpels, the 1 or 2 

 stigmas filiform. Fruit nut-like, 1-seeded. Two known genera, the fol- 

 lowing, and Halodiile. 



