GLOSSARY. 



921 



Protandrous, Proterandrous, used of flowera when 

 the anthers dehisce before the stigmas are receptive. 



Proteid, a nitrogenous substance of complex constitu- 

 tion, generally of a viscid nature and rarely crystal- 

 lizable. The proteids include albumin, globulin, 

 peptone, &c. 



Prothallus, -ium, the structure produced by the ger- 

 mination of the spore of Ferns, bearing sexual organs, 

 and from which the young plant arises and derives 

 nourishment for a time ; also the homologue of this 

 in flowering plants. 



Protogynous, Proterogynous, used of flowers in 

 which the stigmas are receptive before the poUen of 

 the same flower is discharged. 



Protonema, the filamentous growth of a Moss from 

 which the leafy shoots arise by budding. 



Protoplasm, the Hving and formative organic sub- 

 stance of plants and animals ; Hving matter in its 

 simplest form, serving as the basis of both animals 

 and plants, and consisting of carbon, oxygen, hy- 

 drogen, and nitrogen, colourless, transparent or 

 nearly so, and somewhat viscid in consistence. 



Protoplast, the protoplasmic cell-body; a simple one- 

 celled organism. 



Pseudo- hermaphrodite flowers are such as have 

 been functionally unisexual by the suppressing of 

 either stamens or carpels. 



Pseudomorph, a term borrowed from mineralogy ; 

 an unusual or altered form. Cf. vol. i. p. 185. 



Pulverulent, powdery. 



Pulvinate, cushion-like. 



Pulvinus, the enlargement of a petiole or leaf-stalk 

 at its point of insertion on the stem, or of a second- 

 ary petiole at its point of insertion on the leaf -rachis. 



Pycnidium, in Fungi; a receptacle or cavity of vary- 

 ing form, in which conidia (pycno-conidia) are pro- 

 duced : especially in Ascomycetes. 



Pyrenoids, refractive bodies imbedded in the chloro- 

 phyll of many Green Algse. 



Race, a variety or form not distinguished by characters 

 important enough to rank as a species, but repro- 

 duced by seed and transmitting its characters to 

 the offspring ; also loosely used for a group of aDied 

 individuals without regard to rank. 



Racemus, Raceme, an indefinite or centripetal 

 infiorescence with pedicellate flowers. 



Rachis, the axis of a compound leaf, or of a spike or 

 other indefinite inflorescence. 



Radical, belonging to or arising from a root, or from 

 a root-like portion of the stem below the ground. 



Radices adligantes, cUnging roots. 



Radices columnares, columnar roots. 



Radices fulcrantes, stilt-like roots. 



Radices parietiformes, or tabular roots. See vol. i. 

 p. 754. 



Radices tuberosse, or tuberous roots; roots beset 

 with tuber-like enlargements. 



Radicle, the root of an embryo; usually not separ- 

 able from the hypocotyl. 



Radix, the root. 



Raphe, that part of the stalk of an anatropous ovule 

 which is fused with the body of the ovule ; in Dia- 

 toms, the median line on the frustiUe, possibly a 

 sUt. 



Receptacle, of a flower; the abbreviated or flattened 

 axis upon which the various floral members are 

 inserted. 



Reniform, kidney-shaped. 



Replum, the framework, or frame-like placenta, 

 which remains in Cruciferous and other fruits after 

 the valves have fallen away. 



Resilient, springing back, rebounding: used of fruit- 

 stalks, stamens, &c. 



Resin-duct, an intercellular passage into which 

 resin is secreted and where it is stored. 



Respiration, the term applied to the absorption by a 

 plant of free oxygen from, and evolution of carbon 

 dioxide into the air. It is the outward sign of a 

 destructive oxidative process going on within the 

 plant, by means of which latent energy is rendered 

 available. 



Revert, Reversion, a sudden return or breaking back 

 to an ancestral form. 



Revolver-flowers. See vol. ii. p. 249. 



Rhizoids, the hair-like filaments of Mosses and 

 Liverworts, which perform the functions of roots. 



Rhizome, an underground (or prostrate) stem of 

 root-lilie appearance from which roots and her- 

 baceous stems arise. 



Rhizomorph, name given to the curious vegetative 

 phase of Agaricus melleus, which resembles a root. 



Rhizophore, a leafless branch of peculiar construc- 

 tion which, in Selaginella, arises at the place where 

 ordinary branching takes place, and bears roots at 

 its free end. 



Rhizotomoi, a guild of herbalists in ancient Greece. 



Ring, Annual, the zone of wood formed from the 

 cambium in the course of one season in a Conifer or 

 Dicotyledon. 



Ringent, gaping, as the mouth of a bilabiate corolla. 



Ringing, the act of removing from a branch or trunk 

 a circular zone of bark right dovim to the wood. 



Root-cap, the cellular cushion produced at the apex 

 or tip of a root. 



Root-Stock. Same as rhizome. 



Rostellum, the morphological apex of the gynoeceum 

 of an Orchid; usually a beak forming the boundary 

 between the stamen and stigma in Orchids. 



Rosulate, collected in form of a rosette. 



Rotate, wheel-shaped ; circular and horizontally 

 spreading. 



Runner, a prostrate filiform branch which is disposed 

 to root at the end or elsewhere. 



Samara, an indehiscent winged fruit, as the key of 

 the Ash or Maple. 



Saprophyte, a plant which grows on dead and de 

 caying organic matter. 



Scabrous, rough to the touch. 



Scape, or Scapus, a peduncle rising from the ground. 



Scarious, thin, dry, and membranaceous, and not 

 green. 



Schizocarp, a polycarpellary fruit which breaks into 

 1 -seeded portions. 



Sclerotic-cell, a hard, thick-walled cell, often of 

 irregiilar form ; sclerotic cells may be united to- 

 gether into layers, or isolated in soft parenchyma. 



Sclerotium, in Fungi a tuber-like mass of hyphse, 

 which, after remaining dormant for a while, ulti- 

 mately sprouts, producing fructifications. In the 

 Myxomycetes it is the resting-stage of the Plas- 

 modium. 



Scorpioid cyme, a definite inflorescence rolled up 

 towards one side like a crook : common in Boragi- 

 naceae. 



