; 
SWALLOW-WORT. 
have either purple, red, or white flowers; and 
the greater number are most readily propagated 
by radical division. 
The Syrian swallow-wort, Virginian swallow- 
wort, or Virginian silk, Asclepias syriaca, is a na- 
tive of North America, and was introduced to 
Britain in 1629. Its roots are creeping and 
perennial; its stems are annual, erect, un- 
branched, and from 4 to 6 feet high ; its leaves 
are opposite, oval, thick, and downy below ; its 
flowers come out in nodding umbels from the 
junctions of the leaves and stem, and have a 
purple or dull reddish colour, and bloom in July 
and August ; and its pods are long and nearly 
upright, and have a rough coriaceous skin, and 
| contain thin membranous-edged seeds, thickly 
| covered and profusely enveloped with a white 
| down of similar appearance to cotton. The 
| flowers are highly fragrant, especially in the 
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ee me 
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| morning and the evening, and are gathered in 
| their native country while the dew is on them 
/ for the purpose of making sugar; the young 
, shoots, in spring, are a very good substitute for 
asparagus ; the down of the pods serves well for 
stuffing pillows and cushions, for making thread 
and cloth, and for some other purposes ; and the 
fibrous matter of the stems is abundant in quan- 
|| tity, and excellent in flax-like quality, and is 
|| used and highly appreciated in some parts of 
North America for making thread, cordage, fish- 
| ing-nets, and cloth. The plant accommodates 
|, itself to a great variety of soils and situations, 
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| and has been successfully experimented with as 
| an agricultural plant in France, and may pro- 
| bably be well worthy of field cultivation in some 
| parts of Britain. It may be propagated by either 
| sowing seeds or transplanting roots in rows about 
| two feet apart; it must, of course, be kept clean 
| from weeds ; it gradually fills the intervals be- 
| tween the rows by the creeping of its roots, and 
|| arrives at full maturity in the third year after 
|| Sowing; it might be combined in culture, during 
the first and second year, with some annual 
crops which should occupy the vacant spaces pre- 
vious to its maturation, and it will continue in 
full vigour and maintain entire occupancy of the 
soil during a considerable number of years. The 
soil most suitable for it is rather moist, of me- 
dium texture, and of medium fertility. 
The principal medicinal swallow-worts are the 
curassoa, A. cwrassavica, a tropical, perennial- 
rooted, annual-stemmed herb, of about 3 feet in 
height, carrying scarlet flowers from June till 
| September, but comprising also a white-flowered 
variety, and introduced from South America to- 
ward the end of the 17th century; the asthma- 
tic, A. asthmatica, a tropical twiner of about 8 
feet in height, carrying white flowers in July 
and August, and introduced from Ceylon in 
1810; the antidotal, A. alexiaca, a tropical twi- 
ner, of about the same height as the preceding, 
with herbaceous- coloured flowers, introduced 
from Ceylon in 1816; and the decumbent, A. 
SWAN, 389 | 
decumbens, a hardy tuberous-rooted herb, of | 
about 2 feet in height, carrying orange-coloured | | 
flowers in July and August, and introduced from 
North America in 1731. Their chief medicinal 
properties are emetic and sudorific. See the 
article [prcacuaN. 
Among the most ornamental species are the 
pleasing, A. amcna, fibrous-rooted, purple-flow- 
ered, and about 3 feet high; the variegated, A. 
variegata, fibrous- rooted, white - flowered, and 
about 4 feet high; the whorl-leaved, A. verticit- 
lata, fibrous-rooted, white and green flowered, 
and about 3 feet high; the acuminate, A. acu- 
minata, fibrous-rooted, red and white flowered, 
and about 2 feet high; the tuberous, A. ¢uderosa, 
tuberous-rooted, orange-flowered, and about 2 feet || 
high; the roseate, A. rosea, herbaceotisly ever- | 
green, red-flowered, and about 1 foot high; and 
the flax-leaved, A. linzfolia, herbaceously ever- 
green, white-flowered, and about 3 feet high ;— 
all from North America, most blooming in July 
and August, the first five hardy, and the other 
two suited to the greenhouse. 
SWAMP. Moist and soft land akin in charac- 
ter to a marsh or a bog, but differing from both | 
in producing shrubs and trees. See the articles 
Mars and Boa. | 
SWAN,—scientifically Cygnus. A group or | 
subgenus of the duck tribe of lamellirostrous 
palmipedes. They are the largest birds of the | 
tribe ; and are distinguished internally by com- 
paratively long intestines and ceca, and exter- 
nally by a very long neck, and by a bill of equal 
length throughout, higher at its base than it is | 
wide, with the nostrils about the middle of its 
length. 
The tame or domestic or red-billed swan, Cyg- 
nus olor, is the species which, when domesticated, || 
forms the finest living ornament of our ponds and 
water-scenery. It is larger than the wild swan, 
and may readily be distinguished from it by its 
bill_—which has a red colour, edged with black, 
and surmounted at the base by a black rounded 
protuberance or callous knob. The general 
plumage of the bird is snow-white. A cygnet or 
young swan of its species, however, has a lead-~ | 
coloured bill and grey plumage. The domestic | 
swan figures nobly before every eye, and is ad- | 
mired alike by the rustic and the poet, by the 
child and the philosopher; and, in joint virtue 
of the elegance of its form, the gentleness of its 
motions, and the brilliant whiteness of its plum- 
age, it is a fit emblem of beauty and innocence. 
It feeds indifferently on vegetables and fish, eats 
alike bread, seeds, and succulent parts of plants, 
is capable of such familiar domestication as to 
feed from the hand, and requires artificial sup- 
plies of food, and also artificial assistance in the 
breaking of ice and the keeping of ponds open, | 
during the severe parts of winter. It flies ata 
great elevation, and with considerable rapidity ; 
and it swims swiftly, and employs its wings both 
as sails for moving before the wind, and as pow- 
