GLOSSARY. 



915 



O.), a plant resembling a native, but suspected of 

 having been originally introduced. 

 Dentate, of leaf margins ; toothed — the teeth point- 

 ing outwards, not forwards or backwards. 



Dermatogen, the embryonic cellular layer at the 

 apex of a stem or root from which the epidermis 

 is developed. 



Desmid, one of the Conjugatse. See vol. ii. p. 655. 



Dextrorse, used of twining plants which turn from 

 west through south to east, &o. 



Diadromous, having a fan-like arrangement of leaf- 

 veins, as in Gingko. 



Dialypetalae, plants with petals separate from one 

 another ( = Polypetalae). 



Diandria, the 2nd class of Linnean system ; includes 

 all genera with perfect flowers having two stamens. 



Diastase, a soKd, white, soluble substance found in 

 Oats, Potatoes, &c., after germination. 



Diastole, used of the rhythmic expansion of a con- 

 tractile cell or vacuole. 



Diatom, a single organism inclosed in a bivalved 

 siliceous test or frustule. See vol. ii. p. 625. 



Diatomin, the brown pigment of Diatoms. 



Dichogamy, the maturing of pollen and stigma in a 

 hermaphrodite flower at different times, to prevent 

 self-fertflization. 



Dicotyledon, plantwith two seed-leaves or cotyledons. 



Dictyodromous, or reticulate venation, are terms 

 apphed to lateral veins of leaves which break up 

 into a network before reaching the margin. 



Didynamia, the 14th class of the Linnean system, 

 which includes flowers with four stamens, two long 

 and two short. 



Didynamous, applied to flowers having four stamens, 

 one pair longer than the other. 



Dioecious, unisexual; the male and female flowers 

 being on separate plants. 



Diosmosis, the transfusion of a fluid through im- 

 perceptible openings in a membrane. 



Diptero-cecidia, gaU-structures, due to dipterous 

 insects. 



Discoid, resembling a disc. 



Discomycete, any Fungus belonging to the group 

 Discomycetes, i. e. an Ascomycete in which the fruit- 

 ing body is disc-shaped. 



Discomycetous, pertaining to the group of Fungi 

 Discomycetes. 



Discopodium, a disc-shaped floral receptacle. 



Disintegration, a resolution of a tissue into its con- 

 stituent ceEs, or of any body into its constituents. 



Displacement, in whorls, applied to the shifting of 

 places of insertion of members, so that successive 

 whorls are placed immediately above one another. 



Divergence, applied to the angle between the inser- 

 tions of successive leaves on a stem. 



Divided, used of leaf -blades to express the fact that 

 they are deeply lobed. 



Dormant eyes or buds, or Reserve-buds; are buds 

 which arise in the leaf-axils in the usual way, but 

 which do not forthwith expand into sh-oots; they 

 remain — often many years — until stimulated into 

 activity by some special event. 



Drupaceous, of the nature of a drupe. 



Drupe, a succulent fruit with hard, stony endocarp, 

 which incloses a single seed. Many-seeded drupes 

 are rare. 



Duct, a continuous tube, arising either by the run- 

 ning together of cells (fusion), or by the separation 



of cells, when it is lacunar in nature; a canal formed 

 by a row of cells having lost their partitions. 

 Dwarf-male, of ODdogonium; the little few-celled 

 plant arising from an androspore which gives rise 

 to the spermatozoids. It is formed adjacent to the 

 oogonium. 



Ectoplasm, the pellicle-like outmost layer of proto- 

 plasm in a cell. It is clear and hyaline, and less 

 fluid than the endoplasm. 



Egg-cell, or Ovum; the female generative cell. 



Elaters, (1) in Liverworts, filamentous cells, with 

 spiral thickenings, which are present with the 

 spores, and, owing to their hygroscopicity, assist in 

 their dispersal; (2) in Equisetum, arm-like append- 

 ages of the spores, by the contractility of which 

 the spores become entangled in groups. 



Ellipsoidal, having the form of an elliptical soHd. 



Embryo, the rudimentary plant; in seeds, that stage 

 of the young plantlet at which the resting-stage 

 supervenes. 



Embryo-cell, the ceU borne at the distal end of the 

 suspensor, which gives rise to the embryo, or to the 

 greater part of it. 



Embryo-sac, the large cell in the nucellus of an 

 ovule, in which the egg-cell, and ultimately the 

 embryo, arises. 



Endemic, restricted to a given region or locahty. 



Endophytic, Uving within the tissues of another 

 plant, though not necessarily parasitic upon them. 



Endoplasm, the soft, inner granular protoplasm of a 

 ceU. 



Endosmosis, the transmission of fluids through 

 porous membranes from the exterior to the interior. 



Endosperm, the tissue produced within the embryo- 

 sac of flowering plants, and which in many oases 

 beconles stored with food-materials for the embryo. 



Endospores, asexual reproductive cells produced 

 inside the original cells in Bacteria. 



Endothecium, in flowering plants, the layers of the 

 wall of the anther internal to the exothecium. 



Ennobling, the art of transferring a branch or bud 

 of one plant to another, and causing then! to unite. 



Entire, untoothed: applied to the leaf-margin, petals, 

 &c. 



Entomophilous plants, such as have flowers polUn- 

 ated by insect agency. 



Enzyme, any of the unorganized ferments which 

 exist in seeds, as diastase, pepsin, &c. 



Ephemeral, applied to flowers which endure only for 

 a few hours or for a day ; opening but once. 



Epicotyl, the portion of a plant above the cotyledons ; 

 restricted to embryos and seedlings. 



Epidermis, that layer of cells which forms the envel- 

 oping mantle of multicellular plant-bodies. It may 

 be replaced in^ perennial plants by cork. 



Epigeal, growing above the ground. 



Epiphragmi, of Mosses: the membrane remaining 

 after the fall of the operculum, stretched across the 

 mouth of the capsule in Polytrichacese. 



Epiphyllous, applied to structures growing on leaves. 



Epiphytes, plants growing attached to other plants 

 (or animals), but not parasitioally. 



Equitant, riding ; folded around, as if straddling 

 over. 



Erythrophyll, a red sap-pigment frequent in foHage- 

 leaves, especially in autumn. 



