AN ENCYCLOPADIA 
OF HORTICULTURE. 407 
Sedum—continued. 
cymed. l. alternate, ascending, tapering at both ends. Stem | 
green. 
S. T. rhodanensis (Rhone). jl. pink; cymes corymbose, 
globose, long-stalked. 1. alternate, spreading, tapering to the 
base and apex, coarsely toothed. 
S. T. rubella (reddish). . pink; cymes globose, the lower 
ones on long, horizontal stalks, forming an elongated, oblong 
panicle. J. red, ee en to the base, narrow-oblong, coarsely 
toothed. Stems red. 
S. T. thyrsoideum (thyrsoid). f. greenish or yellowish, tin. 
in diameter ; cymes numerous, globose, many-flowered, on long, 
ascending stalks, forming a large, compact panicle. A 
September. l. opposite or whorled; lower ones ascending, 3in. 
by lin., oblong, acute, toothed in the upper two-thirds ; upper 
ones smaller, sub-cordate. Stems about 2ft. high, reddish. 
The following other forms of S. Telephiwm have been mentioned : 
albicans, Bulliardi, Carioni, controversum, corymbiferum, grandi- 
dentatum, inter ium, and Lobellii. 
S. ternatum (ternate). jl. white, lin. across, four-parted: 
sepals oblong, obtuse ; petals oblong, acute, twice the length of 
the sepals ; flower-stems erect. July and Au l. din. long, in 
whorls, of three, sub-orbicular-spathulate, crowded into rosettes 
at the ends of the barren stems; those of the fertile stems 
scattered, ascending or spreading, oblong, acute, Barren stems 
6in. to 8in. long, prostrate. North America, 1789. A glabrous 
bee's 
id 
, Or glaucous evergreen. (B. M. 1977; B. R. 142. 
trifidum (trifid). 
at first reddish, in small, dense, terminal 
es ; petdls linear-lanceolate, twice the length of the lanceolate 
Summer. J. glabrous, aggregated towards the top of the 
tem, sessile, on oblong, cuneate at base, coarsely toothed 
“or pinnatifid. Stems erect, slender, Zin. to 7in. high, unbranched. 
Temperate Himalayas. 
S. umbilicoides (Umbilicus-like). Jl. white, 
inflorescence long-stalked, cymose. 
lanceolate. Alatan, Turkestan. Evergreen. (R. G. 917.) 
SEED. Seeds are met with only in flowering plants, 
and are the result of the union of the male and female 
elements, for the reproduction of the species. They 
are the ovules, fertilised by the action of the pollen, 
and subsequently ripened (see Ovule); and each con- 
tains an embryo (rarely two or more), i.e., a young 
plant, capable, when the Seed is placed, in suitable con- 
ditions, of becoming, in all points, like its parents. The 
existence of an embryo in Seeds affords a sharp distinc- 
tion between them and the spores of Cryptogams, which 
correspond with them in function, but are very often 
one-celled, and never contain an embryo. A reference 
to the account given under Ovule will facilitate the 
explanation of the changes that the ovules undergo in 
seven-parted ; 
FIG. 466. ORTHOTROPOUS OVULE IN SECTION, showing two Coats 
(a, b), with the per an (e), the Nucellus (e), and the Em- 
bryo-sac (d). The ification of the other letters is as follows: 
f is the Funiculus or Stalk ; g, the Raphe, or Fibro-vascular 
Bundle in the Stalk; h, the Chalaza, where the Stalk after- 
wards breaks off, and leaves the Hilum or Scar ; i, the Placenta 
from which the Ovule grows. ati 
becoming Seeds. In the unfertilised ovule (see Figs. 466 
and 467), there are generally two coats, surrounding a 
central cellular massycalled the nucellus; but there is 
a passage (micropyle) at the true apex of the ovule, 
through both coats. In the middle of the nucellus lies 
a large cell, the embryo-sac, formed by the union of two 
or more cells. Within this sac are several cells (see Fig. 
468), viz., at the end next the micropyle two oval or 
elongated cells, the “ helper cells,” with a round cell (two in 
Santalum album) at their inner end, called the embryonal 
tand | 
l. rosulate, convex, oblong- 
Seed—continued. 
vesicle. At the opposite end of the embryo-sac are three 
others, called antipodal cells, which are believed to be 
the last traces of a prothallus, such as is formed in 
Selaginella among Vascular Cryptogams. Among the 
protoplasm that lines the walls of the embryo-sac as a 
thin layer, two nuclei may generally be distinguished. 
After fertilisation, i.e., after the pollen tube has reached 
the embryonal vesicle through the micropyle, the helper 
+ 
Fic. 467. ANATROPOUS OVULE OF ACTA SPICAT 
Only one Coat (@) exists on it (other lettering as in Fig. 466). 
cells and the antipodal cells disappear; the cell w 
of the embryonal vesicle becomes thicker, and the 
grows, and becomes divided by cross-walls. At last it 
forms a cellular mass, the embryo, on the end of - 
suspensor, which part in most plants is a row, but 
some is a mass, of cells. In the embryo of the ripe Se 
it is generally easy to make out radicle, stem, p e, 
and one or two cotyledons. Thus, in it all the vegetative 
oake 
A, 
IN, 
asia 
I 
r 
Fig. 468. EMBRYO-SAC OF ANGIOSPERM 
IN THREE STAGES, 
get! 
the 
well as the Helper Cells are : oe 
organs of the future plant are represented, except. in 
few families (e.g., Orchids), in which the em 
only a mass of cells, without distinction of pa 
Conifere, the course of development of the ovul: 
Seed is different in several respects; but the result 
much the same as regards the structure of the mature 
Seed. While the embryo is in course of development, th 
nuclei of the embryo-sac give rise to the endos 
first, this consists of cells | 
e from one another, but soon 
