GLOSSARY OF BOTANICAL TERMS 317 



Pedicel, the stalk of a single flower of an inflorescence. 

 Peduncle, the stalk of an inflorescence or of a solitary flower. 

 Perennial, a plant which lives for more than two years and 



does not perish after producing flowers and fruit, but 



flowers again the succeeding season; cf. Biennial and 



Annual. 

 Perianth, a floral envelope, not differentiated into two distinct 



series, calyx and corolla. 

 Pericarp, the wall of the ovary as developed in the fruit. 

 Perigynous, applied to flowers where the calyx tube surrounds, 



but does not enclose, the ovary. 

 Petal, a unit of the corolla, or inner series of a differentiated 



floral envelope. 

 Petiole, a leaf stalk. 

 Phanerogam, a Flowering Plant ; a Avide term, including the 



Gymnosperms and Angiosperms. 

 Phyllotaxis, the plan of arrangement of the leaves on the 



stem. 

 Pistil = Gynseceum (q.v.). 

 Pollen, the yellow dust formed in the anthers of the stamens ; 



the male spores which produce the male gametes. 

 Pollen-grains = Pollen. 

 Pollen sac, the sporangium or sac in which the pollen-grains 



are formed in the anther. 

 Pollination, the act of dusting the stigmatic surface of the 



pistil with pollen. 

 Pollinium, the pollen mass of an Orchid (p. 138). 

 Polygamous, bearing hermaphrodite and unisexual flowers on 



the same or different individuals of the same species. 

 Polypetalous, applied to flowers in which the petals are free 



from one another ; cf. Gamopetalous. 

 Prickle, a pointed Emergence {q.v.). 

 Protandry, the form of dichogamy, in which the male organs 



(androecium) mature before the female (gynaeceum). 



