Family 2. ZOSTERACEAE 
By NORMAN TayLor 
Perennial marine plants with creeping rootstocks and flattened, branching 
stems. Leaves all alternate, 2-ranked, linear, flat or complicate, sheathing’ at 
the base. Flowers monoecious or dioecious, arranged on a one-sided spadix 
and enclosed in a close-fitting, ultimately rupturing spathe. Perianth none, 
but some of the flowers covered by a hyaline envelope. Staminate flower of a 
single, sessile, 1-celled anther. Pistillate flower of two united carpels, with a 
short or elongate style and 2 thread-like stigmas. Seeds ribbed or smooth. 
Embryo ovoid or ellipsoid. 
Flowers monoecious; fruits rounded at the base, 1. ZOSTERA. 
Flowers dioecious ; fruits deeply cordate-sagittate at the base. 2. PHYLLOSPADIX. 
1. ZOSTERA L. Sp. Pl. 968. 1753. 
Submerged marine perennials. Stem much branched. Leaves distichous, flat, linear, 
with sheathing stipuliform bases. Inflorescence a peduncled 1-sided spadix enclosed in a 
spathe. Flowers monoecious, arranged in 2 alternate rows on the spadix. Perianth none. 
Staminate flower consisting of a single, sessile, 1-celled anther, attached to the spadix, 
Pistillate flower of 2 united carpels. Style elongate and crowned with 2 thread-like 
stigmas. Mature fruit a flask-shaped utricle, rounded at the base. Seeds sulcate, the ribs 
showing through the testa. Embryo ellipsoid. 
Type species, Zostera marina I,. 
1. Zostera marina I,. Sp. Pl. 968. 1753. 
Zostera marina latifolia Morong, Bull. Torrey Club 13: 160. 1886. 
Zostera oregana S, Wats. Proc. Am. Acad, 26: 131. 1891. 
Zostera pacifica $. Wats. Proc. Am. Acad. 26: 131. 1891. 
Zostera latifolia Morong, Mem. Torrey Club 3?: 63. 1893. 
Stems branched, 1-3 m. long, from a thick rootstock ; leaves linear, distichous, 0.4-1.3 
m. long, 3-13 mm. wide, obtuse at the apex, sheathing at the sessile base, entire or spar- 
ingly dentate; inflorescence a spadix, enclosed in a splitting sheath, bearing alternate 
staminate and pistillate flowers in 2 rows; staminate flowers consisting of a single stamen, 
mostly fugacious ; pistillate flowers consisting of a single stalked or sessile ovary, with a 
slender style and two tapering subulate stigmas; mature carpels cylindric or flask-shaped, 
tipped with the persistent style, smooth or ribbed, according to age, 1-3 mm. long. 
Numerous sterile flowers occur with an apparently abortive perianth. 
TYPE LOCALITY : Baltic Sea. : . 
DISTRIBUTION : Atlantic coast from Greenland to Florida; Pacific coast from Alaska to Cali- 
fornia ; also in the Old World. 
ILLUSTRATIONS: Mem. Torrey Club 3?: A/. 69, 71; Britt. & Brown, Ill. Fl. f. 187; Engl. Bot. 
pl. $67; E. & P. Nat. Pil. 21: f. 155, 156. 
The characters upon which Zz. pacifica S. Wats. (Z. latifolia Morong) were based seem 
scarcely sufficient to maintain the specific status of this western plant. Forms occur in the Pacific 
with both broad and narrow leaves and the lack of any well marked fruit characters makes it im- 
possible to define satisfactory specific limitations. 
The plant upon which Morong (Mem. Torrey Club 3?: 63) bases the occurrence of Zostera 
minor (Cavol.) Nolte in Florida is Cymodocea manatorum Aschers. 
2. PHYLLOSPADIX Hook. FI. Bor. Am. 2: 171. 1838. 
Submerged salt-water perennials. Stems slender, much branched. Leaves linear, 
grass-like, with a sheathing base. Inflorescence a peduncled 1-sided spadix enclosed in a 
VoLuME 17, Part 1, 1909] 29 
