HISTORY AND BIBLIOGRAPHY 869 



Pollen. ^ The fertilizing powder produced in the anthers. 



Pollination. Transferring pollen from anther to stigma. 



Polygamous. Plants bearing both perfect flowers and flowers 

 of either sex, or of both, as in the soft maple. 



Pore-canal. Passage through a pit between adjoining cells. 



Prickles. Short, stiff, spinelike growths from the epidermis, as 

 in the rose. 



Procambium. Fibrovascular tissue of an organ formed before 

 it is differentiated into xylem and phloem. 



Prostrate. Lying flat on the ground. 



Protein. A plant food manufactured in the plant from starch or 

 sugar by the addition of one of the compounds of nitrogen, phos- 

 phorus, potassium or other similar substances. 



Protogynous or proterogynous. Having pistils ready for fertili- 

 zation before anthers are matured. 



Puberulent. Minutely pubescent. 



Pubescent. Covered with fine, soft, short hairs. 



Raceme. A simple indeterminate inflorescence of pediceled flow- 

 ers arranged along a rather long, common axis. 



Rachilla. Axis of spikelet in grasses. 



Raehis. The axis of a spike or other body. 



Radical. Proceeding from the root or base of stem. 



Raphe. The continuation of the seed-stalk along the side of an 

 anatropous ovale or seed. 



Receptacle. Summit of flower-stalk. 



Reflexed. Abruptly bent or turned downward. 



Repand. Having a slightly undulating margin. 



Respiration. Process of absorption of oxygen and giving out of 

 carbon dioxide. 



Reticulated. Net-veined. 



Retrose. Directed backward or downward. 



Rhizome. Any subterranean stem, usually rooting at the nodes 

 and rising at the apex. 



Rib. A primary or prominent vein in a leaf. 



Root. The descending axis of the plant, which supplies it with 

 nourishment. 



Root-stock. See Rhizome. 



Runcinate. Sharply toothed, the teeth directed backward. 



Runner. A slender stolon that roots and forms new plants at 

 intervals. 



Sagittate (leaves). Arrow-shaped, lobes with acute lobes and 

 apex. 



