PLATANACE^l. 201 



6. PIL'EA, Lindl. RICHWEED. CLEARWEED. 

 P. pu'mila, Gray. Stem 3-18 inches high. Leaves ovate, 

 coarsely- toothed, 3-ribbed. Cool moist places. 

 T. iKIinil KIA. Jacq. FALSE NETTLE. 



B. eylin'driea, Willd. Stem 1-3 feet high, smoothish. 

 Leaves ovate-oblong or ovate-lanceolate, serrate, 3-nerve(S, 

 long-petioled. Stipules separate. Moist shady places. 



8. PARIETA'RIA, Tourn. PELLITORY. 



P. Pennsylvan'iea, Muhl. A low annual, simple or 

 sparingly branched, minutely downy. Leaves oblong-lance- 

 olate, thin, veiny, roughish with opaque dots. Usually in 

 crevices of limestone rocks ; not very common. 



9. CAX'NABIS, Tourn. HEMP. 



C. sati'va, L. (HEMP.) Common everywhere along road- 

 sides and in waste places. 



10. HU'MULUS, L. HOP. 



H. Lu'pulus, L. (COMMON HOP.) A twining perennial. 

 Leaves heart-shaped, mostly 3-5-lobed, petioled. Calyx of 

 fertile flower a single sepal. In fruit the calyx, achene. 

 etc., sprinkled with yellow resinous grains, which give the 

 hop its taste and smell. 



ORDER LXXXV. PLATANA'CE^i. (PLANE-TREE F.) 



Represented only by the Genus 



PLAT' ANUS, L. PLANE-TRUE. BUTTONWOOD. 



P. Occident alls, L. (AMERICAN PLANE-TREE or SYCAMORE.) 

 A fine large tree found in south-western Ontario. Leaves 

 alternate, rather scurfy when young, palmately-lobed or 

 angled, the lobes sharp-pointed : stipules sheathing. Flow- 

 ers monoecious, both sterile and fertile ones in catkin-like 

 heads, without calyx or corolla, but with small scales inter- 

 mixed. Ovaries in the fertile flowers club-shaped, tipped 

 with the thread-like simple style, and downy at the base. 

 Fertile heads solitary, on slender peduncles. The white 

 bark separates into thin plates. 



