AN ENCYCLOPADIA 
507 
OF HORTICULTURE. 
Stocks—continued. 
separated and placed aside, because it has been ascertained 
that the plants coming from the seeds situated in this 
portion of the pod give eighty per cent. of single fiowers. 
They yield, however, greater variety than the others. 
This plan of suppressing that part of the pod which 
yields single flowers in the largest proportion, greatly 
facilitates the recognition of the single-flowered plants, 
because there remains to be eliminated from among the 
seedlings only from ten to fifteen per cent.” 
This separation of the single from the double-flowered 
plants, M. Chaté tells us, is not so difficult as might be 
supposed. The Single Stocks, he explains, have deep green 
leaves (glabrous in certain species), rounded at the top, 
the heart being in the form of a shuttlecock, and the 
plant stout and thickset in its general aspect; while the 
plants yielding double flowers have very long leaves of a 
light green colour, hairy, and curled at the edges, the 
heart consisting of whitish leaves, curved so that they 
completely inclose it. 
Such is the substance of M. Chaté’s method of securing: 
so large a proportion of double-flowered plants, and then 
of separating them from the remaining single ones—a 
method which commends itself to the good sense of the 
intelligent cultivator. ` 
Another plan for the separation of the single from the 
double-flowered plants, in vogue amongst a class of cul- 
tivators, is the degustation of the buds, that is to say, 
the chewing of the young buds: the single plants can be 
recognised by their crispness and greater consistence, and 
can thus be weeded out. The disadvantage attending this 
method is that the plants, single as well as double, must 
all be grown up to the period when these buds are 
tolerably well advanced. 
STOCK, TEN-WEEEKS. 
Mathiola annua (which see). 
STOCK, VIRGINIAN: A common name for Mal- 
colmia maritima (which see). 
STGCHAS. Included under Lavandula. 
STOKES’ ASTER. See Stokesia cyanea. 
A common name for 
Fic. 542. STOKESIA CYANEA 
STOKESIA (named in honour of Jonathan Stokes 
M.D., 1755-1831, the coadjutor of Withering in his 
` exposed to daylight. 
| Stokesia—continued. 
arrangement of British plants). Syn. Cartesia. ORD. 
Composite. A monotypic genus. The species is a hand- 
some, sparingly - branched, greenhouse, erect, perennial 
herb. It thrives in the open border during the summer 
months. Propagation may be effected by seeds, or by 
division of the roots. 
S. cyanea (blue).* Stokes’ Aster. /.-heads blue, lin. across, few 
or solitary, terminal, pedunculate; involucre sub-globose, the 
outer scales prolonged into a leafy, bristly-fringed appendage, 
the inner ones lanceolate and entire ; florets narrowly five-cleft ; 
pappus ae Sag of four or five chaffy scales. August. l. alter- 
nate, smooth, lanceolate, entire or spinuloso-ciliate at base ; 
lower ones petiolate ; upper ones amplexicaul. Stem lft. to lift. 
high. North America, 1766. See Fig. 542. (B. M. 4966.) 
STOLE; or STOLON. A branch arising from near 
the base of the parent stem, resting on the soil, rooting 
at the tip, and finally tending to form a new plant, 
capable of independent growth when the branch is cut, 
or dies away, between the terminal bud and the parent 
plant. Certain modifications of Stolons have received 
distinctive names, of which the more important are: 
Offset, a short Stolon (e.g., Sempervivum), and Runner, 
a very slender Stolon, with long, naked internodes (e.y., 
Strawberry). 
STOLONIFEROUS. Bearing, or propagating by, 
stolons, runners, &c. 
STOMA (plural, Stomata; from stoma, a mouth), The 
Stomata are little openings, or mouths, in the outer cover- 
ing or epidermis of the green parts of plants, through 
which they may be said to breathe. The air passes into 
the plant from the outside, bringing with it Carbonic Acid 
gas. This gas is broken up in the cells containing chloro- 
phyl: all the Carbon, and half of the Oxygen, of the 
Carbonic Acid are retained by the plant, to be built up 
into starch, and other foods; and half of the Oxygen 
escapes from the plant into the outer air, through the 
Stomata. The air passing out is loaded with vapour of 
water evaporated from the cells of the leaf; and thus 
there is a constant escape, through the Stomata, of water 
from green parts of plants. The form and structure 
of the Stomata do not vary much in vascular plants; 
though many groups of these plants exhibit peculiarities 
in the form and arrangement of the cells of the epidermis 
that lie round the Stomata, and that are often called the 
“neighbour-cells’”’; but it is not necessary here to enter 
upon a description of the latter. The Stoma, or opening, 
lies between two sausage -shaped cells, called “ guard- 
- cells,” which are joined near the ends, but leave a space 
between them in the middle. This opening leads into 
an empty space between the cells, below the epidermis, 
from which space crevices pass in all directions, opening 
into larger ones among the loosely-arranged cells in the 
middle of the leaf. There is a constant passage of gases 
into and out of the cells through the thin cell-walls 
that border the inter-cellular spaces, with results upon 
the atmosphere as stated above, if green plants are 
The guard-cells are usually green, 
owing to the presence in them of chlorophyl. They thus 
present a contrast to the ordinary cells of the epidermis, 
which contain few, if any, chlorophyl-bodies in land 
plants, except in Ferns, and a few others. The guard-cells 
regulate evaporation from plants, since they swell when 
full of sap, and become more convex, thus leaving 
a wider opening between them when a plant contains 
much sap and would benefit by the evaporation of some 
of it. In dry weather, when there has been much evapora- 
tion, the guard-cells contain less sap, and thus become 
straighter, and leave a narrower slit; so that evapora- 
tion becomes much slower through the Stoma when it 
requires to be diminished in amount. Stomata seldom 
occur on parts of plants habitually under ground, or under 
water, where they would be useless. They are most 
abundant on leaves, especially on the lower surface, ex- 
cept in some Conifers, and a few other plants, in which 
