GLOSSARY 855 
Rhizome. See Rootstock. 
Rootstock. A horizontal, more or less thickened, root-like stem, either 
on the ground or underground. 
Saprophyte. An organism that obtains its food from dead or decay- 
ing organisms. 
Scalariform (ladder form). A name applied to ducts with piths hori- 
zontally elongated, and so placed that the intervening thickening ridges 
appear like the rounds of a ladder. 
Scale (a flight of steps). Any thin scarious body, as a degenerated 
leaf, or flat hair. 
Sclerenchyma. A tissue composed of cells that are thick-walled, often 
extremely so. 
Seed. The matured ovule. 
Sepal. A calyx leaf. 
Seta; pl. sete. A bristle, or bristle-shaped body; in mosses, the stalk 
of the capsule. 
Sexual spore. One formed by the union of cells. 
Sheath. A thin enveloping part, as of a filament, leaf, or resin duct. 
Sieve cells. Cells belonging to the phloém, and characterized by the 
presence of perforated plates in the wall. 
Sorus (a heap); pl. sori. In ferns, the groups of sporangia, constitut- 
ing the so-called “fruit dots”; in parasitic fungi, well-defined groups 
of spores, breaking through the epidermis of the host. 
Sperm, or Spermatozoid (animal-like sperm). The male gamete. 
Spermatophytes (seed plants). The highest great group of plants, of 
which a characteristic structure is the seed. 
Spike. A flower cluster, having its flowers sessile on an elongated 
axis. 
Spikelet (diminutive of spike). A secondary spike; in grasses, the 
ultimate flower cluster, consisting of one or more flowers subtended by 
a common pair of glumes. 
Sporangium (spore vessel); pl. sporangia. The spore-producing 
structure. 
Spore (seed). Originally used as the analogue of seed in flowerless 
plants; now applied to any one-celled or few-celled body which is sepa- 
rated from the parent for the purpose of reproduction, whether sexually 
or asexually produced; the different methods of its production are in- 
dicated by suitable prefixes. 
Sporogonium (spore offspring); pl. sporogonia. The whole structure 
of the spore-bearing stage of bryophytes. 
Sporophyll. A leaf that bears sporangia. 
Sporophyte (spore plant). The asexual or spore-producing stage of 
an alternating plant. 
