GLOSSARY. 



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Petalody. — The change into a foliar organ having the colour 



and consistency of a petal. 

 Petiole. — Leaf-stalk. 



Petiolule. — Stalk of leaflet, or subdivision of leaf. 

 Photophilous. — Growing in the light. 



Phyllode. — A foliage-leaf devoid of leaf-blade, and in which 

 the petiole has become flattened and more or less leaf- 

 blade-like. 



Phyllody. — The change to a foliage-leaf. 



Phyllome. — The category to which all foliar organs belong. 



Phyllotaxis. — The leaf-arrangement on the stem. 



Pliylogeny. — The evolutionary development of the race. 



Physiological. — Relating to the life-functions of the organism. 



Phytqn. — The unit, composed of leaf -blade and its basal 

 part or stalk, which is the fundament of stem structure ; 

 on the " phyton-theory 33 every stem is essentially built 

 up of a sympodially-developed succession of phyton- 

 units. The phyton is the true Individual. 



Pileus. — The cap, or spore-bearing part ; = flower or fruit of 

 toadstool. 



Pinnate. — Lateral incision of a leaf to form two or more 

 leaflets. 



Pinnatifid. — Of a leaf, laterally incised half-way, or rather 



more than half-way to the midrib. 

 Pinnatisection. — Marginal incision of the leaf as far as the 



midrib. 



Placenta. — The region in the ovary on which the ovules are 

 inserted. 



Pleiomerous. — Having a large number of parts or organs. 

 Pleiotomy. — Multiple apical division; formation of multi- 

 plets. 



Plerome. — The layer or layers which give rise to the central 

 cylinder. 



Plumule. — The portion of the embryo and seedling developed 

 above the insertion of the cotyledons. 



Podosyncarpy. — In which the double capsule of a moss has 

 one half fully developed and the other half abortive. 



Pollen-sac. — One of the fertile divisions of the anther, con- 

 taining the pollen ; homologous with a sporangium. 



Postgenital. — Occurring after birth. 



Primary node. — The region of the axis at which the first- 

 formed leaves or cotyledons are inserted. (Applied to 

 Dicotyledons and Grymnosperms.) 



Primordial leaves. — The foliar organs first formed after the 

 cotyledons. 



