4 86 



EXPLANATION OF TERMS. 



Progamous cell. Cell formed in the pollen- 

 grain which has the sperm-nucleus. 



Prolification of flower. Production of 

 terminal and lateral leaf-buds in the 

 flower. 



Promycelimn. In Uredineae and Us- 

 tilagineae : a short and short-lived 

 tubular product of germination of a spore, 

 which abjoints a small number of spores 

 (sporidia) unlike the mother-spore and 

 then dies off. 



Pronucleus. Nucleus of a conjugating 

 gamete which on coalescing with another 

 pronucleus forms the germ-nucleus. 



Protandry. Maturity of the androecium 

 before the gynaeceum in a hermaphrodite 

 flower ; a form of dichogamy. Comp. 

 protogyny. 



Prothallium. In Vascular Cryptogams 

 and Angiosperms : a thalloid oophyte 

 or its homologue. 



Protogyny. Maturity of the gynaeceum 

 before the androecium in a hermaphrodite 

 flower ; a form of dichogamy. Comp. 

 protandry. 



Protomeristem. Primary meristem, i. e. 

 meristem forming the first foundation of 

 a member. 



Protonema. In Muscineae : pluricellular 

 confervoid or plate-like structure upon 

 which the conspicuous plant bearing 

 sexual organs is developed as a lateral or 

 a terminal shoot. 



Protophloem. First formed elements of 

 phloem in a vascular bundle. 



Protoxylem. First formed elements of 

 xylem in a vascular bundle. 



Pseudaxis. Same as sympodium. 



Pseudocarp. See fruit. 



Pseudopodium. In Musci : elongated 

 extremity of a branch of the oophyte in 

 the form of a stalk supporting a sporo- 

 gonium or bearing gemmae. 



Pullulation. Mode of cell multiplication 

 in which a cell forms a small protuberance, 

 this enlarges to the size of the mother 

 cell, becomes cut off from it by the for- 

 mation of a dividing wall at the narrow 

 point of junction, and finally separates 

 from it entirely. Same as sprouting. 



Pulvinus. Enlargement of petiole at its 

 point of insertion. 



Putamen. Indurated endocarp in a drupe. 



Pycnidium. In Ascomycetes : special 

 receptacle in which spores (gonidia) 

 termed stylospores (also pycnospores 

 and pycnogonidia) are abjointed from 

 sterigmata. 



Pyrenocarp. Same as perithecium. 



Pyxidium. Capsule with circumscissile 

 dehiscence. 



Raceme. Simple racemose monopodial 



inflorescence with primary axis elongated 

 in region of branching and flowers pedi- 

 cellate. 



Racemose. A monopodial branching is 

 racemose when the mother-axis continues 

 to elongate and produce daughter-axes 

 by none of which is it overtopped. 



Radial. A member developing uniformly 

 on all sides around its longitudinal axis 

 is radial. Comp. dorsiventral. 



Radicle. Portion of embryo below coty- 

 ledons consisting of hypocotyl and primary 

 root. 



Ramentum. See palea. 



Raphe. Portion of funiculus in anatropous 

 ovule extending along whole length of 

 ovule and adherent to the integument. 



Raumparasit. Same as aulophyte. 



Receptacle. Term of varying signifi- 

 cation. In this book used to denote : 

 (a) in Marchantieae : special outgrowth 

 of thallus bearing sexual organs ; (b) in 

 Filices : placenta. 



Receptive spot. Hyaline spot in an 

 oosphere at which the male gamete 

 enters. 



Regular. Of flower: same as actino- 

 morphous. By English and French 

 writers the term is used with reference 

 to the flower to denote equality in size 

 and form in the members of calyx and 

 corolla. 



Rejuvenescence. Transformation of whole 

 of protoplasm of a previously existing cell 

 into a cell of a different character. 



Replum. Frame of a siliqua formed by 

 united margins of the two carpels and 

 across which the spurious dissepiment 

 is stretched. 



Resting cell. Isolated cell which has 

 passed into a quiescent or dormant state. 



Resting spore. See resting cell. 



Rhachis. A primary or main axis. 



Rhizine. Same as rhizoid. 



Rhizoid. Filamentous structure analogous 

 with a root found on compound thalli 

 of all kinds and on the stems of Muscineae. 



Rhizome. Dorsiventral creeping or sub- 

 terranean stem sending up annually aerial 

 shoots from the extremity of its branches. 



Rod-fructification. In Basidiomycetes : 

 special simple gonidiophores. 



Rotation of protoplasm. Streamingmove- 

 ment of protoplasm following the contour 

 of a cell i. e. in the primordial utricle, as 

 in cells of Characeae. 



Ruminate endosperm. Endosperm mot- 

 tled on section ; due to unfolding of a 

 dark inner layer of the seed-coat into 

 the lighter coloured endosperm. 



Samara. Winged achene or winged meri- 

 carp of a schizocarp. 



