GLOSSAUY. 



921 



Protandrous, Proterandrous, used of flowers when 

 the anthers dehisce before the stigin>as are receptive. 



Proteid, a nitrogenous substance of complex constitu- 

 tion, generally of a \-iscid 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 stigm;is are receptive before the pollen of 

 the same flower is discharged. 



Protonema, the filamentous growth of a Moss from 

 wliich tlie leafy shoots arise by budding. 



Protoplasm, the living and formative organic sub- 

 stance of plants and animals ; living matter in its 

 simplest form, scrWng as the basis of both animals 

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

 drogen, and nitrogen, colourless, transp.irent 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-Hke. 



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 Algae. 



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 allied 

 individuals without regard to rank. 



Racemus, Raceme, an indefinite or centripetal 

 inflorescence with pedicellate flowers, 



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

 other indetinite inflorescence. 



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

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



Radices adligantes, clinging roots. 



Radices columnares, columnar roots. 



Radices fulcrantes, stilt-like roots. 



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

 p. 754. 



Radices tuberosae, 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 frustule, possibly a 

 slit. 



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 tlie outward sign of a 

 destructive oxidative process going on «itliin 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. 2-19. 



Rhizoids, the hair-Uke filaments of Mosses and 

 Liverworts, which perforin the functions of roots. 



Rhizome, an underground {or prostrate) stem of 

 root-like 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 pecuUar construc- 

 tion which, in SelagineUa, 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 remo\ing from a branch or trunk 

 a circular zone of bark right down 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 gj-nreceum 

 of an Orchid ; usually a beak forming the boundary 

 between the stamen and stigma in Orchids. 



Rosulate, coDected 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- 

 capng 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 

 irregular form ; sclerotic cells may be united to- 

 gether into layers, or isolated in soft parenchyma. 



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

 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 IJoragi- 

 nacea;. 



