GLOSSARY. 277 



PLANE or PLAIN A flat, level, smooth, even surface. 



PLASTICITY Retaining any impressed form or shape. 



POLLEN (Bot.) The male element in flowering plants, usually a fine 

 dust produced by the anthers, which by contact with the stigma 

 effects the fecundation of the seeds. This impregnation is brought 

 about by tubes (pollen tubes) which issue from the pollen grains 

 adhering to the stigma and penetrate through the tissues until 

 they reach the ovary. 



POLYGAMUS PLANTS Plants in which some flowers are unisexual and 

 others hermaphrodite. 



POURRIDIE (French) Disease on the roots of vines caused by different 

 fungi. 



PROCREATION Generation or production of young. 



PRODUCTIVITY The quality or state of being productive. 



PROTUBERANCE A swelling or prominence, such as the protuberance 

 of a node. 



PUBESCENT Covered with fine short hairs, as the leaves of some vines. 



QUATERNARY TUFA (Geol ) A soft, porous stone formed by deposition 

 from water, usually calcareous, belonging to the quaternary age. 



RADICEL (Bot.) A small branch of a root; a rootlet. 



RAPHE or RHAPHE (Bot.) The continuation of the seed stalk along 

 the side of an anatropous seed, forming a ridge or stem. 



REVERSION To return towards some ancestral type or character; 

 atavism. 



RIB (Bot.) The chief nerve or one of the chief nerves of a leaf; also 

 any longitudinal ridge on a stem, as in V. Berlandieri. 



ROUNDED LEAF Having a curved outline without lobes. 



RUDIMENTARY Very imperfectly developed; in an early stage of 

 development. 



RUGOSE, leaf Having the veinlets sunken and the spaces between 

 them elevated. 



SCHIST Any crystalline rock having a foliated structure. 



SCHISTOSE SOILS Are usually metamorphic clays. 



SCION A piece of branch cut for grafting into another. 



SEMI Prefix signifying half, as in semi-erect, semi-climbing habit, etc. 



SEPALS The leaves or segments of the calyx, or outermost envelope 

 of an ordinary flower. They are usually green. 



SHOULDERED GRAPES Those in which the two ramifications of the 

 base are well developed. 



SIEVE TUBFS (Bot.) Also called cribriform tubes. Those having 

 here and there places perforated with many holes. 



SILICA Quartz, silicon dioxide. 



SILICEOUS NODULES See Nodule. 



SILICEOUS OR SILICIOUS SOILS Those containing silica or quartz. 



SILURIAN (Geol ) A term applied to the earliest of the Palaeozoic 

 strata. 



SINUS (PI. sini or sinuses) A depression between adjoining lobes in a 

 leaf. 



SPECIES An ideal group of individuals which are believed to have 

 descended from common ancestors, which agree in essential 

 characters and are capable of indefinitely continued fertile repro- 

 duction through the sexes. A species as thus defined differs from 

 a variety or sub-species only in the greater stability of its charac- 

 ters and in the absence of individuals intermediate between the 

 related groups. 



