324 THE KINDS OF PLANTS 



8. ASPIDIUM. SHIELD FERN. 



Resembles Polystichum but with reniform indusia or, if circular-peltate, 

 having a distinct sinus along one side. 



A. Thelypteris, Swartz (Dryopteris The- 

 lypteris, Gray). Marsh shield fern. Fronds 

 standing 2 ft. high, long-pointed, once-pin- 

 nate, the pinnae many-lobed, the margins of 

 the fertile fronds revolute. 



A. marginale, Swartz (Dryopteris mar- 

 ginalis, Gray). Fig. 480. Large, handsome 



fern growing in woods and ravines, 2 ft. 

 4oU. Aspidium marginale. . . , ., . 



high: fronds once-pinnate, the pmnce pinna- 



tifid and lance-acuminate: sori large and close to the margin of the frond: 

 petiole chaffy. 



AA. PHENOGAMS: B. GYMNOSPERMS. 

 II. CONIFERS. CONE-BEARING or PINE FAMILY. 



Woody plants, mostly trees, with resinous sap and stiff needle- 

 shaped or scale-like, mostly evergreen leaves: plants bearing no ovaries, 

 the ovules lying naked and receiving the pollen directly: flowers 

 diclinous (usually monoecious), generally in scaly catkins, those cat- 

 kins bearing the pistillate flowers maturing into cones but sometimes 

 becoming berry-like (as in junipers). Above 300 species, one-third 

 of which inhabit North America: particularly abundant in elevated 

 and mountainous regions. 



A. Cone dry, with overlapping scales. 



B. Scales many and cones 1 in. or more long. 



c. Leaves long and needle-like, in sheaths or bundles of 



2-5, persistent 1. Pinus 



cc. Leaves short, scattered, persistent. 



D. In cross-section, Ivs. 4-sided: sessile 2. Picea 



DD. In cross-section, Ivs. flat: short-petioled 3. Tsuga 



ccc. Leaves short but very slender, in clusters, deciduous. 4. Larix 



BB. Scales few (3-12), the cones about Yi in. long 5. Thuja 



AA. Cone modified into a fleshy, berry-like body 6. Juniperus 



1. PiNUS. PINE. 



Trees with long, persistent, needle-shaped, angled leaves, in bundles of 

 2-5, and with scale-like deciduous leaves on the young branchlets: sterile 

 catkins usually borne at the base of the new shoot: fertile cones maturing 

 the second year, often hanging on the tree for years: cotyledons several. 



P. Strdbus, Linn. White pine. Figs. 158, 299. Large forest tree, much 



