516 GLOSSARY 



Head, a globose, or flattened, compact flower cluster, the flowers with short 



stalks, 150, 153, 166. 

 Helicoid cyme (Hel'-i-coid), a flower cluster where the terminal flower opens 



first and the successive lateral branches all arise on the same side and 



extend above the previous one forming a curved flower cluster, 151, 152. 

 Heliotropism (He-li-ot'-ro-pism), a turning influenced by the light, said of 



leaves, stems and roots when their position is influenced by the light, 30. 

 Hermaphrodite (Her-maph'-ro-dite), a flower having both stamens and 



pistils, 145. 

 Heterosporous (Het-er-os'-po-rous), bearing other sorts of spores, applied 



to the higher Pteridophytes and seed plants which have two kinds of 



spores, large and small, 379, 386. 

 Heterospory (Het-er-os'-pory), the condition of having two kinds of spores, 



large and small, 402, 417. 

 Heterothallic (Het-er-o-thal'-lic), applied to thallus plants (particularly to 



certain fungi or algae) the individuals of which are of different sex 



nature, either male or female, 278, 279, 337, 347, 379, 382. 

 Hilum, the scar on a seed where it separates from the stalk, 6, 9; the central 



spot on certain starch grains, 21. 



Homosporous (Ho-mos'-po-rous), bearing like spores, 379. 

 Homothallic (Ho-mo-thal'-lic), applied to thallus plants the individuals of 



which have both sexes on the same individual, 279, 347. 

 Honey guide, bright colored lines or spots on petals of certain flowers leading 



to the nectaries, 188. 



Host, the plant or animal on which a parasite grows, 134, 308. 

 Humus, plant matter partially decayed with limited supply of air, found in 



forests, and certain swamps, dark brown in color, 125. 

 Hydrophytes (Hy'-dro-phytes), fresh- water plants or plants of very damp 



situations, 458. 



Hygrophyte (Hy'-gro-phyte), = hydrophyte, 458. 

 Hymenium (Hy-me'-ni-um, plural, hymenia), the fruiting surface of fungi 



where numerous sporophores are crowded together making a distinct 



surface, 323, 324. 

 Hypha (Hy'-pha), a single thread of mycelium, or a branch from the same, 



273, 35- 

 Hypocotyl (Hy-po-cot'-yl), the portion of the stem of a seedling which lies 



between the cotyledons and the radicle, 7, 8, 10, 12, 16. 

 Hypogynous (Hy-pog'-y-nous) , said of flower parts which are free from the 



pistil and arise from the receptacle, 147, 157. 

 Hypo nasty (Hy'-po-nas-ty), the curving upward or inward over the bud, 



of leaves when the growth is more rapid on the under side, 86. 

 Hypothecium (Hy-po-the'-ci-um), the sterile tissue beneath the asci in the 



ascocarp, 301. 



