16 



MISC. PUBLICATION 110, U. S. DEPT. OF AGRICULTURE 



flower (perianth), showing a close 

 relationship to lilies. Sedges have 

 3-ranked leaves and usually solid 

 stems which are often triangular in 

 cross section. The floral organs of 

 sedges are in the axils of 2-ranked or 

 spirally imbricated (i. e., more or 

 less overlapping) scales and, in the 

 case of the largest and most familiar 

 genus, Carex, the pistillate (female) 

 flower is enveloped in a sac called 

 the " perigynium." Because the 

 majority of rushes and sedges grow 

 in wet sites, grasslike plants are 

 sometimes called " marsh grasses " 

 or " wet meadow grasses." The 

 term " grasses " for them, however, 

 is inaccurate and misleading. 



Gymnosperm : Literally, naked seed. 

 A member of the Gymnospermae, one 

 of the two main groups into which 

 flowering, or seed-producing, plants 

 are customarily divided, the other 

 being the Angiospermse. Gym- 

 nosperms (to which pines and other 

 conifers belong) have the ovules and 

 seeds borne on a naked scale ; an 

 enveloping ovary, as well as a true 

 floral envelope (perianth) and 

 stigmas are wanting. Botanically 

 gymnosperms are a primitive and 

 relatively rather small group, but 

 economically they are of the highest 

 importance — to the forester probably 

 the most important of all. 



Gynaecandrous: A term applied to 

 those sedges {Carex spp.) which 

 have male and female flowers in 

 the same spike but the upper flowers 

 female, so that only the upper part 

 of the spike bears 

 fruit. The con- 

 verse of androgy- 

 nous. 



Habit : Aspect ; man- 

 ner of growth. 



Habitat: The site or 

 environment which 

 a plant or plants 

 (as well as ani- 

 mals) natively oc- 

 cupy, and the 

 study of which is 

 the science of ecol- 

 ogy. 



Halophyte: A plant 

 adapted to exist- 

 ence in a saline 

 environment, as 

 greasewood, salt 

 grass (Distichlis), 

 and the saltbushes 

 (Atriplex spp.). 



Hastate: Shaped like a spear or hal- 

 berd head, the basal lobes pointing 



Figure 34. — Has- 

 tate leaf of 

 sheep sorrel 

 (Rumex aceto- 

 sella) 



outward and usually much shorter 

 than the blade. (Fig. 34.) 



Haw: A hawthorn {Crataegus sp.) or, 

 more especially, its fruit; a small 

 pome, or hip, as in a rose. This 

 form of fruit is caused by the fleshy 

 enlargement of the hypanthium. 



Head : A headlike formation, especially 

 a rounded, congested inflorescence 

 or seed cluster ; the characteristic 

 inflorescence of the aster, or com- 

 posite family (Asteracese, or Com- 

 posite ). In a true head (capitu- 

 lum) the individual flowers are ses- 

 sile or nearly so. 



Helicoid: Shaped like the spirally 

 coiled shell of a snail (Helix). 

 (Fig. 35.) 



Heliotropism : Response in a plant to 

 the stimulus of sunlight; the turn- 

 ing or growth of the 

 aerial portion of a 

 plant to light ema- 

 nating from the sun 

 (Greek, helios) ; as 

 in the radicle and 

 plumule of the em- 

 bryo. 



Hemi -: A prefix 

 (Greek) signifying 

 half. 



Herb: A phanerogam 

 (flowering plant), 

 the aerial portion 

 of whose stem is 

 destitute of woody tissue and per- 

 ishes when flowers and fruit are 

 matured. An herb may have an an- 

 nual, biennial, or perennial root, 

 but the aerial stem is ordinarily 

 annual ; when a stem survives into 

 the second or ensuing seasons there 

 is naturally a tendency for w T oody 

 tissue to form and for the transition 

 to shrub or tree status to ensue. 



Herbaceous : Of or pertaining to herbs ; 

 having the characteristics of an herb 

 and free from woody tissue. 



Hermaphrodite: A word (both noun 

 and adjective) used to describe an 

 individual having the organs, char- 

 acteristics, qualities, or attributes 

 of both sexes. Said specifically, in 

 botany, of a perfect flower, i. e., one 

 containing both pistils and stamens. 



Heterogenesis: Same as alternation of 

 generations. 



Hexamerous: Having the parts in 

 sixes (Greek, hex, six, + meros, 

 part). 



Hilum: The scar on the surface of a 

 seed which shows the place of de- 

 tachment of the matured ovule from 

 its base or seed stalk. 



Hirsute: Hairy with rather coarse, 

 stiffish, straight, beardlike hairs. 



Figure 35. — 

 Helicoid 

 pod of al- 

 falfa 



