PINACEAE. 23 



vious year ; ovule-bearing aments terminal on year-old t branch- 

 lets; bract somewhat shorter than the cone-scale; cones maturing 

 the first year, pendulous. 



Leaves 8-18 mm. long; cones 2 cm. long. T. heterophylla. 



Leaves 12-25 mm. long; cones 5-7 cm. long. T. mertensiana. 



Tsuga heterophylla (Raf.) Sarg. Western Hemlock. Handsome tree, 

 30-60 m. tall and 50-200 cm. in diameter; branches slender, usually bent down- 

 ward; leaves linear, flattened, unequal in length, 8-18 mm. long; cones oblong, 

 10-16 mm. long. 



A common forest tree, most abundant at about 1000 m. altitude. It ranges 

 from Prince William Sound, Alaska, to Marin County, California. It was 

 originally described by Lewis and Clarke from the mouth of the Columbia 



River - 



mertensiana (Rnng.1 Cnrr. Mn^n^rr B7//. f fe Tfpm.I.nrt Tree 

 30-50 m. high and 50-200 cm. in diameter; leaves 1-2 cm. long, acutish, 

 convex above, bearing stomata on both surfaces; cones oblong, dark purple, 

 5-7 cm. long. 



Common in the mountains at about the limit of trees; at the highest altitude 

 it becomes a prostrate shrub. The Black Hemlock ranges from Prince 

 William Sound, Alaska, where it occurs at sea level, southward in the moun- 

 tains to Montana and California. It was first found by Mertens an the moun- 

 tain at Sitka. 



~ 



Ovules (megasporangia) enclosed in a cavity (the ovary) 

 formed by the infolding and uniting of the margins of 

 a modified rudimentary leaf (carpel), or of several such 

 leaves joined together, in which the seeds are ripened; 

 stigmas present; cotyledons one or two, very rarely want- 

 ing; perianth present or wanting. 



Sub-class I. MONOCOTYLEDONES. 



Embryo of the seed with but a single cotyledon, that is 

 with the first leaves of the germinating plantlet alternate; 

 stem composed of a mass of soft tissue in which the woody 

 bundles appear in cross section to be irregularly imbedded, 

 there being no distinction into bark, wood and pith; 

 leaves usually parallel-veined, mostly alternate and entire, 

 commonly sheathing the stem at the base and often with 

 no distinction of blade and petiole; parts of the flowers 

 mostly in threes. 



Family 10. TYPHACEAE. CAT TAIL FAMILY. 



Marsh or aquatic herbs with creeping roots tocks and linear 

 lat sheathing leaves; stems erect, terete; flowers monoecious, 



