Merrimack and Connecticut rivers or in the upland west of the Merrimack 

 River, although Sunapee Mountain lies ahout at the boundary intended 

 here. Southern New Hampshire includes all of Rockingham. Hillsborough, 

 and Cheshire counties, about half of Stratford County, the southern part of 

 Merrimack County, and the southernmost part of Sullivan Countw 



We have endeavoured to designate the elevations at which the various 

 species are to be found whenever there might be any question. The term 

 "low elevation" refers to areas from to 1,500 feet; "medium elevation" 

 refers to areas from 1,500 feet to tree-line which occurs almost exclusivelv 

 m the Presidential and Franconia ranges and varies from 4,500 to 5,000 

 feet, rarely descending to the 4,000-foot level. "Alpine areas" or "alpine 

 zone" refers to the region above tree-line occupied by low shrubs, herbs, 

 or bare rock. Many of its plants have Arctic at^nities. In addition to the 

 above-mentioned ranges, small alpine areas occur on Guyot and Bond 

 mountains in the Twm i\ange as well as above the cliifs of Mt. Cannon 

 and on the summit of Mt. Moosilauke. "Subalpine" applies to the occasion- 

 al areas, mostly in the floors of ravines in the Presidential Range, where 

 the trees are much stunted and conditions rather resemble the alpine area. 



All of southeastern Xew Hampshire is at low elevation. In southwestern 

 New Hampshire there are a number of scattered mountains of elevations 

 u]^ to 2,400 feet, with Monadnock an isolated peak at 3,100 feet. Much of 

 central New Hampshire is low, but with frequent uplands and mountain- 

 ous areas reaching 2,500 feet and occasionally 3,000 feet. Most of northern 

 New Hampshire is of medium and high elevation, the principal river val- 

 leys being exceptions, and also the considerable area approaching the Con- 

 necticut Vallev in northwestern Grafton and western Coos counties. 



Climate is without doubt an important factor governing the distribution 

 of plants in New Hampshire. The average annual precipitation varies 

 from 38 to 46 inches at low and medium elevations ; it is highest in extreme 

 n.orthern New Hampshire and lowest in a band across the state near 

 Colebrook and along the Connecticut at Charlestown and Walpole. The 

 higher mountains may receive up to twice as much. The average annual 

 temperature varies from 40° to 45 °F. being lower in the north and in- 

 creasing southward. .Average temperatures for July at low and medium 

 elevations vary from 66° F. in the far north to 68° F. in the center and to 

 70° F. in some parts of extreme southern New Hampshire, while January 

 averages vary from as low as 12°F. in the far north to as high as 22° F. in 

 the southeast. The length of the growing season as determined by the 

 riumber of consecutive days without killing frosts varies from an average 

 figure of 100 days in the northernmost part to 140 in the southernmost 

 area. Much of northern and central New Hampshire, apart from the higher 

 mountains, has about 120 consecutive frost-free days. The frost-free grow- 

 ing season is perhaps of greater importance in determining agricultural 

 potentialities than in affecting native woody vegetation, since the native 

 perennial species are only rarely harmed even by unseasonable frosts. In 

 a general way it is ])()ssible to correlate the more pronounced vegetational 

 types with the regional climates within the state. 



The major soil types also show a fair degree of correlation with the 

 vegetational associaticms. This is to be expected in view of the fact that 

 vegetation plays an important role in the genesis of soils. Typical podzols 

 are found over much of the state except for the areas of low elevation in 



