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Pyrenoid, a small, definite, rounded, colorless body 
occurring in a chloroplast and serving as a center 
of starch accumulation. 
Pyriform, pear shaped. 
Quadrate, four sided, square. 
Racemose, arranged in a cluster of branches along a 
central axis, the branches becoming of approxi- 
mately equal lengths and having the older ones 
below. 
Radial, radiating, as from a center. 
Ramulus (pl., ramuli), a small branch. 
Receptacle, the enlarged fruiting portion of the 
plant, bearing the sunken cavities (concep- 
tacles), in the Fucacee. 
Reticulate, forming a network. 
Rhizoid, a cellular filamentous outgrowth serving 
as an organ of attachment. 
Rhizoidal, pertaining to rhizoids. 
Rhizome, a creeping portion of a thallus resembling 
a horizontal stem and giving off upright stem- 
like or leaflike branches. 
Rimose, having cracks in the surface, as in the old 
bark of trees. 
Rotund, rounded in outline, but a little inclined 
toward oblong. 
Scutellate, shaped like a small platter. 
Secund, bearing branches or organs on only one 
side of an axis. 
Septate, bearing septa. 
Septum (pl., septa), a partition. 
Seriate, arranged in series or rows. 
Serrate, bearing numerous short, sharp, marginal 
teeth, like those of a saw. 
Serration, the bearing of serrate teeth. 
Sessile, borne directly on the axis, not on a stalk. 
Setaceous, very slender and rigid, bristlelike. 
Silique, the peculiar pod of the mustard family. 
Sinus, the more or less acute angle formed by the 
division of a thallus into approximately equal 
parts. 
Sorus (pl., sori), a definite cluster of reproductive 
organs. 
Spatulate, oblong, with the basal end attenuated, 
like a spatula. 
Spermatangium (pl., spermatangia), a more or less 
specialized organ bearing male cells. 
Spermatium (pl., spermatia), a nonmotile male cell, 
occurring in the Rhodophycez. 
Sporangiferous, bearing sporangia. 
Sporangium (pl., sporangia), a specialized organ 
bearing spores formed nonsexually. 
Spore, a cell specialized for propagation and cap- 
able, without fusion with any other cell, of grow- 
ing into a new plant. 
BULLETIN OF THE BUREAU OF FISHERIES. 
Sporocarp, a fruit produced as a result of the fer- 
tilization of the egg in the carpogonium, includ- 
ing the carpospores and the accessory structures, 
occurring in the Floridee. 
Stellate, star shaped. 
Stichidium (pl., stichidia), a specialized branch 
bearing tetrasporangia, occurring in a few Flor- 
idex. 
Stipe, the narrow, stemlike stalk by which a flat- 
tened thallus is attached. 
Stipitate, possessing a stipe. 
Stolon, a horizontal, stemlike portion which, at- 
taching itself and becoming separate from the 
parent, forms a new plant. 
Sub-, used as a prefix to denote somewhat, to a 
limited degree, as subacute; used as a prefix to 
denote under, as subcortex. 
Substratum, the underlying substance on which a 
plant is growing. 
Subulate, subuliform, awl shaped, long, slender, 
and pointed. 
Sympodial, having an arrangement where each 
branch forms a part of the main axis, the result- 
ing axis thus being formed partly from the 
branches, but resembling a simple axis. 
Synonym, an incorrect name used for a species 
which has a correct name. 
Taxonomic, referring to the classification of plants 
according to their relationships. 
Terete, cylindrical and usually tapering, circular 
in cross section. 
Tetrahedral, four sided, used especially with refer- 
ence to apical cells, and sometimes to tetra- 
sporangia which are triangularly divided. 
Tetrasproangium (pl., tetrasporangia), a sporan- 
gium whose contents are divided into four spores, 
occurring in the Floridee and the Dictyotacez. 
Tetraspore, one of the four spores formed in a tetra- 
sporangium. 
Tetrasporic, bearing tetraspores, frequently used 
with the same meaning as asexual. 
Thallus, a plant body not distinctly differentiated 
into stem and leaf. 
Tortuous, bent or twisted in different directions. 
Torulose, cylindrical, with swollen portions at in- 
tervals, somewhat moniliform. 
Triangular, a method of division of a tetrasporan- 
gium by four walls formed in different planes and 
meeting at the center, three of the resulting 
tetraspores usually being visible on a single 
surface, each appearing triangular in shape. 
Trichoblast, a filamentous, lateral outgrowth con- 
sisting of a single row of cells, usually much 
branched, borne on the surface of a thallus. 
