INDEX 



469 



Hazel, pollen of, carried by wind, 300. 



starch in, during winter, 259. 

 Hazel, Witch, dispersal of seeds, 321. 

 Heart wood, 244, 245. 

 Heat, as preservative, 386. 



effect of, on absorption by root, 332. 



bacteria, 363, 364. 



— — — direction of growth of stem and 



root, 88, 89. 



— — — evaporation, 115. 

 flora, 351, 356. 



flower and fruit production, 347. 



— — — growth, 252. 



leaf, 345. 



Mould. 394. 



opening and closing of flowers, 



296. 

 effect of on plants, 352, 353, 354.* 355-358. 

 transformation of fat into 



starch, 259. 



transpiration, 207. 



entrance of, into seed, 42, * 43. 



excessive, injurious, 352. 



of respiration, 35, 36*, 287. 



lack of, kills plants, 352-354. 



prevents chlorophyll formation. 



354.* 



— — preserves foods, etc., 386. 



— — produces rosette form, 357. 

 needed by plant, 326. 



— to awaken seed, 4, 5,* 6. 

 set free by flowers, 287. 

 seeds, 35, . 6.* 



Heath plants love sour humus, 351. 



protection of, against drying, 213, 333. 

 Helianthus. See Sunflower. 

 Heliotropism, 264. 346. 

 Hemizonia. See Tarweed. 

 Hen • and • chickens, protection of, against 

 drying. 215. 



storage of water by, 334. 



transpiration of, 216. 



water reservoirs of, 215. 

 Herb Robert, protection of pollen of, 295. 

 Hereditary percentage, 436, 442. 

 Heredity, 411,* 413,* 416,* 422, 423,* 424,* 

 425*, 426,* 427,* 428, 429,* 434, 436. 442. 

 Hickory, flower-buds of, 286. 



path of water in. 226. 



Hickory, preparation for flowering of, 286 



seed-cover of, holds water, 29. 



wood of, 230. 

 Hieracium. See Hawkweed. 

 Hilgard, acknowledgment to, x. 



— on soils, 126,* 160. 

 Hilum. 1,* 2. 



as place for entrance of water, 10. 

 Hippuris, 342. 

 Histology of flower, 290,* 291.* 



— fungi, 395,* 396,* 397,* 399,* 402,* 403,* 



404,* 407.* 



— leaf. 196-198.* 199*-201,* 202,* 208,* 



209,* 333, 334,* 335,* 336.* 337,* 338,* 

 340,* 344,* 345,* 402,* 403,* 404.* 



— leaf-stalk, 212. 



— root, 120,* 121. 



— seed, 65,* 66, 67, 177, 178. 



— stem, 224*-227,* 228-230.* 231, 232,* 233, 



234*-236,* 267,* 268,* 328. 333,* 334,* 

 335.* 

 Holly, cuticle of. 334.* 



protection of. against animals, 222. 



drying, 333, 334.* 



transpiration of. 204. 

 Hollyhock, rust of, 40fr. 

 Holmes, on fertilizers, 153. 

 Honey. See Nectar. 



Honey Locust, protection of. against ani- 

 mals. 222. 

 Honeysuckle family, cross - pollination of. 

 303. 



flower, position of, 307. 

 Hop, cross-pollination of, 302. 



dispersal of seeds of, 322-323.* 



twining of, 275. 

 Hopkins, work of, 434-439. 

 Horehound, hairy covering of leaf, 213. 

 Hornblende, 107. 

 Hornwort, 339. 

 Horse-beau, germination of, 81, 82,* 86. 



micropyle of, 10. 



seed of, stnieture of, 1,* 2. 



seed-leaf of, contrasted with foliage leaf 

 180-186. 



function of, 178, 179. 



microscopic structure of, 65,* 66. 



Horse-chestnut, flower-buds of, 286. 



hairy covering of leaf of, 213. 



