GLOSSARY OF BOTANICAL TERMS 



33 



tubes with their companion cells 

 compose the soft bast (sieve tissue) 

 or phloem of the outer fibrovascular 

 bundles of the higher plants. The 

 sievelike partitions permit the 

 strands of protoplasm, or living tis- 

 sue, to extend through the tubes and 

 facilitate the transportation of the 

 products of assimilation, of which 

 transfer the sieve tubes are the chief 

 agency. 



Silicle: A small silique, especially one 

 that is as broad as or broader than 

 long; as the silicles of pepperwort 

 and shepherd' s-purse. 



Silique: The peculiar, mostly elongat- 

 ed, 2-valved capsule or pod of the 

 mustard family (Brassicacese, or 

 Cruciferse). 



Simple: Unbranched or undivided; 

 said, for example, of stems, leaves, 

 and inflorescence; the opposite of 

 compound. A simple pistil is one 

 carpel, representing morphologically 

 a single folded leaf. 



Sinistrorse: Spirally twisting to the 

 left. Said of vines that twine in a 

 clockwise direction, as bindweed and 

 morning-glory- 

 Sinuate: Strongly wavy margined; 

 more deeply wavy than undulate, or 

 repand. 



Sinus : The depression between two ad- 

 joining lobes (literally gulf or 

 bosom). 



Sorus (pi. -ri) : A fruiting dot on the 

 fertile frond of a fern; an assem- 

 blage of sporangia. 



Sp.: Species (singular) ; pi. spp. 



Sp. nov.: New species (Latin, species 

 nova). 



Sp. PL: Species Plantarum (an impor- 

 tant work of Linnaeus, the first edi- 

 tion of which, published in 1753, is 

 regarded by both the International 

 and American Codes as the starting 

 point of binomial plant nomencla- 

 ture). 



Spadix: A floral or fruiting spike with 

 a thickened fleshy axis, usually 

 densely flowered, the flowers often 

 more or less imperfect, and charac- 

 teristically subtended by a spathe. 

 This type of inflorescence is charac- 

 teristic, for example, of the arum 

 family (including callas, jack-in-the- 

 pulpits, skunkcabbage, and sweetflag 

 or calamus). 



Spathe: An enlarged, membranous, 

 sheathing bract or bracts subtending 

 an inflorescence, and especially the 

 characteristic bract (often colored) 

 associated with a spadix as the 

 spathe of a jack-in-the-pulpit or 

 calla lily. 



Spatulate: Shaped like a spatula; i. e., 

 broad and rounded at apex and with 

 a narrowed, relatively short base. 

 (Fig. 38, D.) 



Species (pi. species) : A group of indi- 

 viduals with so many characteristics 

 in common as to indicate a very high 

 degree of relationship and a common 

 descent. The unit of plant and ani- 

 mal classification. White pine (Pinus 

 strobus), aspen {Populus tremu- 

 loides), Colorado columbine (Aqui- 

 legia cwrulea), and the domestic 

 horse (Equus caballus) and sheep 

 (Ovis aries) are familiar illustra- 

 tions of species. Genera are com- 

 posed of species, which in turn often 

 comprise various subspecies and va- 

 rieties. 



Specific: Of or pertaining to a species, 

 as a specific character or specific 

 name. 



Spermatophyte: A seed-producing 

 plant ; a phanerogam. 



Spiciform: Having a spikelike form, 

 as the spiciform panicle of timothy. 



Spicule: A very small, needlelike yet 

 more or less fleshy body, appendage, 

 or point as, for example, the spicules 

 of cacti. 



Spike: An elongated flower cluster in 

 which the flowers are sessile, i. e., 

 without indi- 

 vidual flower 

 stalks (pedi- 

 cels). Wheat, 

 spearmint, and 

 mullein are fa- 

 miliar examples 

 of plants whose 

 flowers are 

 borne in spikes. 



Spikelet: A name 

 applied to each 

 of the main 

 components of a 

 grass or sedge 

 inflores- 

 cence. ( Fig. 

 68.) A grass 

 spikelet usually 

 consists of two 

 glumes and one 

 or more florets ; 

 it may be erect 

 or pendulous, 

 sessile, or pedi- 

 cellate. Grasses are distinguished 

 primarily by differences of spikelet 

 construction. 



Spine: A sharp-pointed, rigid, deep- 

 seated emergence from a plant. 

 Spines differ from prickles in not 

 pulling off with the bark (epidermis) 

 of the plant ; they differ from thorns 

 by absence of vascular tissue. 



Figure 68. — A, Spike- 

 let of Kentucky 

 blue grass (P o a 

 pratensis) : a — f s 

 lemmas (with their 

 inclosed organs 

 forming florets) ; 

 g~h, glumes ; B, 

 lemma of same 

 showing arachnoid 

 (cobwebby) hairs 

 at base 



