182 GLOSSARY. 



Perithecium, pi. perithecia (around the case). The spore- 

 vessel of certain Carpophytes, containing the spore-sacs 

 (asci). 



Petal (a leaf). A corolla-leaf. 



Petiole (a little foot). The stalk of a leaf. 



Phanerogamia (evident marriage). A primary division (the 

 highest) of plants, named, from their mode of reproduc- 

 tion, the seed-producing plants. Phanerogam is the 

 English equivalent. See Spermatophytes. 



Phloem (the inner bark). The bark or bast portion of a fibro- 

 vascular bundle. 



Photosynthesis (light construction). The name applied to the 

 process through which chloroplasts under the influence of 

 sunlight manufacture such carbohydrates as starch and 

 sugar from water and carbon dioxid. 



Phycocyanin (blue seaweed). A bluish coloring-matter found 

 within certain Algas. 



Phyllotaxy. Leaf-arrangement. 



Pinna, pi. pinna (a feather). One of the primary divisions 

 of a pinnate leaf, as in ferns. 



Pinnule (a little feather). One of the divisions of a pinna. 



Pistil (a pestle). A simple or compound carpel in Spermato- 

 phytes. 



Pit. A thin place, or pit-like depression, left in the thickening 

 of a cell-wall. 



Placenta, pi. placentae (a cake). That portion of the ovary 

 which bears the ovules. 



Plerome (that which fills). A name given to that part of 

 the meristem, near the growing points of the plant-axis, 

 which forms a central shaft or cylinder and develops into 

 the axial tissues. 



Plumule (a little feather). The terminal bud of the embryo 

 above the cotyledons. 



Pod. A dry, several-seeded, dehiscent fruit; or a similar spore- 

 case. 



Pollen (fine flour). The spores developed in the anther. 



Pollen-tube. The structure that develops from the wall of 

 the microspore on Spermatophytes and carries male cells 

 to the egg. 



Pollination. The transfer of pollen to the stigma. 



Polypetalous (many petals). Applied to flowers that have 

 their petals free from one another, 



