68o 



BOTANY OF THE LIVING PLANT 



Homologous alternation, 381, 384, 



390, 543, 54 6 - 

 Homology, 343 (Chap, xx.) ; denned, 



344- 

 Homoplastic development, 342 (Chap. 



xx.). 



Homoplasy, where similar morpho- 

 logical results are produced by 

 adaptation in two or more distinct 

 evolutionary lines, 192, 342 ; in 

 Algae, 375. 



Homosporous, applied to archegoni- 

 ate plants in which there is only 

 one type of spore, 352 ; a primitive 

 state, 520 ; fully exploited in 

 Pteridophytes, 553. 



Homothallic condition, in Mucorales, 

 where zygospores are produced on 

 meeting of two branches of the 

 same mycelium, 416 ; in Rusts, 



439. 



Homotype-division, the second divi- 

 sion in the spore-tetrad, carried 

 out like any somatic division, 

 565 (Fig. 430). 



Homozygote, formed by union of 

 two gametes similar in respect of a 

 given character, or characters, 572. 



Honey Agaric, parasitism of, 393 

 (Fig. 292) ; 445. 



" Honey Dew," 395 (Fig. 293) ; 425 

 (Fig. 323). 



Hooks, in seed dispersal, 328 (FigC 



251)- 

 Hop, twining stem of, 215. 



Hop-mildew (Sphaerotheca), 420 



(Figs. 318, 319) ; 421. 

 Hordeum (Barley), analysis of, 660 ; 



origin of, 661. 

 Horizontal microscope, 145. 

 Hormidium, 365. 

 Hormones, 148 ; in geotropism, 157 ; 



in phototropism, 160. 

 Hornea, 352, 478 (Fig. 372 a). 

 Horse-chestnut (Aesculus), 13 (Fig. 



6), 80 (Fig. 55). 

 Horsetails, vegetative propagation 



of, 252 ; characters of, 522 (Fig. 



413 a). 

 Host, a plant or animal that supplies 



food to a parasite, 220. 

 Host-cells in mycorrhiza, 231 (Fig. 



159). 



Humble-bee, agent for pollination of 

 Aconite, 302. 



Humus, leaf-mould, decaying vege- 

 table matter of the soil, 96, 221. 



Hura (Sand-box Tree), explosive fruit 

 of, 165 (Fig. 102) ; dehiscence of 

 fruit, 324, 630. 



Hyacinth, qualities of fibres of, 178 ; 



perennation of, 198 (Fig. 132). 

 Hybrid, the offspring of a cross be- 

 tween parents belonging to distinct 



races or species, 568-581. 

 Hybridisation, the breeding together 



of members of distinct races or 



species, 568-581. 

 Hydrodictyon, the Water-Net, 365. 

 Hydrom, water-conducting tissue of 



Mosses, 464 (Fig. 358). 

 Hydrophytes, plants adapted to life 



in presence of plentiful water, 



212. 

 Hydrotropism, response to stimulus 



of unequal water-supply, 160. 

 Hygroscopic movements, due to 



changes in degree of moisture, 



165 (Figs. 100-103) ; of seeds and 



fruits, 324. 

 Hymenial gonidia, algal cells in the 



hymenium of a Lichen, 429. 

 Hymenium, the layer bearing asci 



or basidia, in Fungi or Lichens, 



428 ; of Hymenomycetes, 442 



(Fig. 387) ; of Mushroom, 442, 



445. 

 Hymenomycetes, 441. 



Hypertonic, and hypotonic solutions, 



35- 

 Hypha, the fungal filament, 393 ; 



non-septate, 399 ; septate, 399 ; 

 traversing tissue of host, 395 (Fig. 

 294. 404 ( Fi g' 302), 407 (Fig. 

 306). 



Hypholoma, 400 (Fig. 299), 431. 



Hypobasal tier, the part of an embryo 

 lying below the basal wall : in 

 Ferns, 504. 



Hypocotyl, region of stem below the 

 cotyledons, n (Fig. 4), 58; struc- 

 ture of (Fig. 37). 



Hypoderma, tissue below the epider- 

 mis, often mechanically strength- 

 ened, 74. 



Hypodermal cells, those lying below 

 the epidermis, 284. 



Hypogynous, of flowers, with stamens 

 and other outer parts seated 

 below the gynoecium, 271 (Fig. 



195)- 

 Hypophysis, cell giving rise to the 



root-tip in the embryo of Dicoty- 

 ledons, 311 (Fig. 230). 

 Hypo-rachis, 351. 



Ice in tissues, 148. 



Iceland Moss (Cetraria), 428. 



Imbibition, water of, 5, 33, 96. 



