AIR. 



AIRA. 



called Foul Meadow Grass. The last name 

 being evidently derived from the great difficulty 

 with which it is eradicated when it has once 

 obtained a footing. The grass called white-top, 

 appears to be a variety of Herds. There 

 seems to be considerable obscurity and confu- 

 sion -in the descriptions given of this grass. 

 The common characteristics of the plant, as 

 seen in the meadows of Pennsylvania, Dr. 

 Darlington says, resemble those of the A. alba, I 

 the White or Yellow Tops of the Eastern States. ' 

 It affords a tolerably good pasture for cattle, 

 and is valuable in swampy grounds, which its 

 roots tend to consolidate ; but it is not much 

 esteemed for hay, and is now seldom, if ever, 

 an object of special cultivation in the Middle 

 States. The Pennsylvania farmers are so op- 

 posed to having Herds grass rooted in their 

 fields and meadows that they reject clover and 

 every other grass seed in which the least 

 Herds appears. Among the species found in 

 the United States, are the following 



A. pungens, or VirginianAgrostis, frequenting 

 dry, sandy banks, and road-sides, flowering in 

 the southern part of Pennsylvania, in August. 

 This species differs much, in habit, from most 

 others. 



A. cinna, common on rivers and islands be- 

 low tide-water, from Canada to the Carolinas, 

 ilowering in June, &c. 



A. jnncea, found in barren, sandy places, 

 from New Jersey to Florida ; flowering from 

 July to August. 



_1. laterifolia, found in rich soil on the 

 edges of woods from New York to Florida, 

 especially in the western countries, where it 

 appears to be of more value. In the southern 

 parts of Pennsylvania it affords an indifferent 

 pasture in the latter part of summer, but is not 

 regarded as of much consequence, which may 

 indeed be said of most, if not all, of the Ame- 

 rican species of agrostis. 



The late Judge Peters introduced the florin 

 into Philadelphia county, in 1812, by import- 

 ing a quantity of the strings or layers from 

 which it is always propagated in Ireland. For 

 some reason its cultivation has not been kept 

 up, and at present it is difficult to be found in 

 America. When once it has obtained a foot- 

 ing in a suitable soil, it is scarcely to be 

 eradicated, for which reason it is not adapted 

 to the alternate system of husbandry.] 



AIR (Air, French, aer, Lat). The element 

 or thin medium in which terrestrial animals 

 move and breathe, and which surrounds the 

 earth to a considerable height. See ATMO- 

 SPHERE and GASES. 



AIRA. A genus of grasses, of which there 

 are but few species capable of being cultivated 

 to advantage as field grasses. 



Aira aquntica. Water hair-grass. This plant 

 is an aquatic, found naturally growing in the 

 mud of standing pools, or running waters in 

 England. It is, therefore, unfit for cultivation. 

 Mr. Curtis says, that it is the sweetest of the 

 British grasses ; but there are several species 

 wrich contain more sugar, in proportion to the 

 otner ingredients which compose their nutri- 

 tive matter, as the Glyceria fluitans, Elymus 

 arenarius, Poa ntmoralia var. angustifulia, Poa 

 aquatica. 

 56 



Aira csespitosa. Turfy hair-grass ; hassock 

 grass. [See Plate 6. of PASTURE GHASSKS, /.] 

 This grass is of a very innutritious nature ; 

 but even if it had greater nutritive powers, the 

 extreme coarseness of the foliage would render 

 it unfit for cultivation. It delights in moist 

 clayey soils, where the water stagnates; but is 

 found in almost every kind of soil, from the 

 dry sandy heath to the bog. It forms dense 

 tufts in pastures very disagreeable to the sight, 

 which are termed hassocks, bull's faces, &c., 

 by farmers. It is a most difficult plant to ex- 

 tirpate, when in considerable quantity. Some 

 persons, to get rid of it, dig up the tufts, and 

 fill up the holes with lime compost ; this, no 

 doubt, would answer the end, at least for a few 

 years, if all the roots were destroyed ; but this 

 is never the case: a circle of roots is left, 

 which, in one or two seasons, produce larger 

 hassocks than before ; and besides, when the 

 hassocks are numerous, the expense attending 

 this process is considerable. Others depend 

 on occasional mowings to keep the hassocks 

 under; but this is productive of little good, 

 particularly if the mowing of the tufts be de- 

 ferred till the autumn, which I believe is the 

 common practice. I have found no treatment 

 weaken or retard the growth of grass so much 

 as cutting it closely, before and after the first 

 tender shoots appear in the spring. But the 

 only effectual and most profitable mode of ex- 

 tirpating this grass is by first paring and burn- 

 ing the surface of the land, and by making 

 proper drains, to correct, as much as possible, 

 the tenacious nature of the soil ; in this case 

 surface-drains are as necessary as those 

 termed hollow. Sand should likewise be ap- 

 plied during the course of crops taken previous 

 to returning the land again to permanent pas- 

 ture, if such should be desirable, from its local 

 situation ; as that, for instance, of a park or 

 policy. This grass flowers about the third 

 week in July, and the seed is ripe towards the 

 end of August. 



Aira cristata. Crested hair-grass. Poa cris- 

 tata. Crested meadow-grass. Host. ii. p. 54, 

 t. 75. This native grass was formerly ranked 

 by botanists under the genus Poa, but has 

 since been referred to that of Aira, to which it 

 is more closely allied. The produce of this 

 species, and the nutritive matter it affords, are 

 equal to those of the Festuca ovina at the time 

 the seed is ripe ; they equally delight in dry 

 soils, though the Aira cristata will thrive well 

 and remain permanent in soils of a moist and 

 clayey nature, which is different from the Fes- 

 tuca ovina. The greater bulk of the produce 

 of the Aira cristata, in proportion to its weight, 

 makes it of inferior value to the Festuca ovina. 

 In some parts of the country it grows on dry 

 pastures plentifully, where it appears to be but 

 sparingly eaten by cattle, particularly if the 

 pasture be not overstocked. Rye-grass (Lo- 

 lium perenne), sheep's fescue (Festuca ovina}, 

 yellow oat-grass (Avena flavescens), crested 

 dog's tail (Cynosurus cristatus}, meadow barley 

 (Hordeum pratense), flexuose hair-grass (Aira 

 flexuosa}, are all preferred by cattle to the 

 crested hair-grass. The nutritive matter of 

 this grass differs but little in its composition 

 from those of the above : it approaches nearest 



