Peduncle, 62. Peltate, 77. Perennial, 17. Pericarp, 164, 165, 169. Petals, 134. Petiole, 76. Phenogam, 177, 180. Photosynthesis, 94, 101. Phyllotaxy, 84. Pine cone, 27, 170. Pinna, 181. Pinnate, 74. Pinnatifid, 76. Pistil, 135. Plantain, 157. Plant societies, 9. Plants, unlikeness of, 9. Plumule, 20, 23, 25. Plur-annual, 18. Pod, 164. Pollen, 135, 144, 180. Pollination, 144, 145; artificial, 153. Polypetalous, 134. Polysepalous, 134. Polytrichum, 199. Pome, 169. Primrose, 140. Propagation by buds, 121. Prop-roots, 36. Proterandrous, 146. Proterogynous, 146. Prothallus, 178, 202. Protoplasm, 42, 94, 97, 185. Pruning, 105. Pseud-annual, 17. Pteridophytes, 181, 201, 203. Puffball, 194. Pyxis, 166. Quarter-sawed, 70. Receptacle, 134, 163. Respiration, in plants, 97, 103. Resting spore, 184, 185, 189, 191, 192. Rhizome, 52, 202. Root cap, 44. Root climber, 129. Root hairs, 41, 42, 46. Rootlet, 41. Root pressure, 99, 104. Roots, and air, 41; forms of, 32; function, 38; structure, 38, 43; systems, 32. Rust, 192. Samara, 164. Sap, 67. Saprophyte, 107, 108. Scape, 161. Scion, 125. Scouring rush, 203. Scramblers, 129. Seed, 20, 163, 180; coat, 21. Selaginella, 204. Selection, natural, 8; artificial, 8. Sepal, 133, 169. Septicidal capsule, 166. Sessile, 77. Shelf fungus, 194. Shrub, 19. Sieve tubes, 66. Silicle, 167. Silique, 167. Societies, 9. Soil, 40, 47. Soredia, 196. Sori, 177, 192. Spadix, 140. Spathe, 138, 140. Spermatophytes, 180. Spike, 157. Spirogyra, 184. Sporangium, 177, 186, 188, 201, 203, 204. Spore, 176, 178, 181, 184. Sporophyll, 180, 201. Sporophyte, 177. Stamen, 135. Starch, 95, 101. Stem, 49; endogenous, 59; exogenous, 61; kinds of, 49. Stigma, 135, 144, 145. Stipule, 76, 84. Stock, 125. Stomate, 87. Stone fruit, 168. Storage of food, 99. Struggle to live, 4, 6. Style, 135, 163. Summer-spore, 191. Sun energy, 95. Survival of fittest, 7. Swarm-spores, 186. Symbiosis, 196. Syngenesious, 141. Teleutospores, 192. Tendril, 101. Thallophyte, 181, 184. Thallus, 184, 197. Thorns, 101. Thyrse, 160. Tillandsia, 110. Timber, decay of, 195. Tissue, 60, 62. Toadstool, 194. Torus, 134, 169. Tracheid, 65.