i 
de 
THE DICTIONARY OF GARDENING, 
* 
Veslingia—continued. 
involucral bracts somewhat biseriate; receptacle convex 
or conical; ray florets ligulate, three-toothed at apex; 
achenes glabrous. Leaves opposite or the k ones 
alternate, entire or toothed. Only one speci calls for 
description here. It thrives in any rich soil, and may be 
increased by seeds. % 
V. sativa (cultivated). 
. rather me; involucre simple, of 
and — i. amplexicaul, cordate-lanceolate, remotely 
= serrated. h. 6ft. 1806. SYN. Verbesina sativa, (B. M. 1017.) 
.. Guizotia oleifera is now the correct name of this plant. 
VESPA. See Wasps. 
VESPERTINE. Appearing or expanding in early 
evening. 
ji-heads golden-yellow, 2in. across, 
ve leaflets. August 
|  WESPUCCIA (commemorative, in honour of Amerigo 
= Vespucci, 1451-1512, after whom America is named). 
Hydrocleis is now the correct name of this genus. ORD. 
Alismacee. A small genus (three or four species) of 
highly glabrous, stove, aquatic herbs, inhabiting tropical 
South America. Flowers solitary, large, hermaphrodite, 
on long, thick peduncles; perianth segments six, the 
three outer ones (sepals) persistent, the three inner ones 
(petals) yellow, larger, very slender, deciduous; stamens 
numerous, hypogynous, in many series. Leaves fascicled, 
floating, ovate- or cordate-orbicular, the nerves con- 
verging at the apex; petioles thick, sheathing at base. 
here, is of easy culture in a tub or cistern of water. 
It may be readily increased by seeds, or by runners. 
V. Humboldtii (Humboldt's) fl., se narrow. a ; 
pu broadly pom eie e end Man. grece 
ertile or sterile; peduncles E gie p from the nodes, one- 
May. l, both radical and cauline ones broadly ovate 
or sub-orbieular, obtuse, loosely cordate at base, 2in. to An. 
in. to gin. b , coriaceous ; petioles terete, din. to 
fc (a Uu oe 
the correct name of this plant. [pte 
VESSELS. In the vascular system of vascular 
plants (i.e., the flowering plants and higher Crypto- 
gams), Vessels are found plentifully; but they do not 
occur in any groups of plants lower than the Ferns and 
their allies, though the laticiferous cells of a few Fungi 
are a good deal like them in appearance. 
Vessels may be grouped as follows: 1. True Vessels, 
being those of the fibro-vascular bundles, which compose 
the vascular system. These comprise (a) Vessels of the 
Wood (* xylem ”) and (b) Vessels of the Bast (* phloem ") 
or sieve-tubes. 2, Vessels of the Cellular Tissue, or 
Ground Tissue, scattered through the pith and cortex 
of the roots and stems, and among the green cells of 
leaves. These three classes of Vessels differ materially 
in their nature, contents, and uses. The two classes 
of true Vessels agree in being present in all complete 
fibro-vascular bundles ; and also in being always formed 
by the absorption of the walls that separate elongated 
cells placed in rows, either end to end, or overlapping 
more or less at the tapering ends, so that tubes are 
thus formed of indefinite length. In most Vessels it is 
easy to trace the cells of which they are formed by the 
marks that remain on the walls where the cells meet. 
The Vessels of the Wood differ from those of the Bast 
in several. important respects. But before stating these 
it may A ry elucidate the subject if a brief account 
of the ordinary structure of fibro-vascular bundles is given. 
We shall select for description such a bundle as ma; be 
found in the stems of many Monocotyledons In th 
plants the bundles usually remain separated from € 
another, during their whole existence, by the cellular em 
in which they are imbedded; and after they : 
formed they do not undergo changes, so that See is Se 
ment of the cells and Vessels of which they are. bui 
up is little, if at all, altered during growth. The in Ki 
bundles of this kind consist of a group die Sec, 
is now 
V. Humboldtii, the only species calling for description ` 
Vessels—continued. 
of the Wood (called *trachesm ”), united with a group of 
Vessels of the Bast (“ sieve-tubes ”); but in most parts 
of plants these are accompanied by cells, some of 
which are elongated and slender (fibre-cells or “ prosen- 
chyma ") while others are little, if any, longer than broad 
(*parenchyma"). Some of the cells usually remain thin- 
walled; but others have the walls much thickened by 
deposits upon the inner surface, and then the tissue is 
called * sclerenchyma." This tissue adds to the strength 
of the bundle, being arranged alongside the Vessels 
(as wood-fibres.or hard-bast fibres), or forming a sheath 
surrounding the bundle entirely or in part. The com- 
monest position of the wood and bast of each bundle, 
as seen in transverse section, is that in which the wood 
lies nearer the centre of the stem, and the bast nearer 
the circumference; but in some plants there is bast 
inside, but not outside, of the wood, or there may be 
bast both inside and outside, or even all round the wood. 
Less often the bast lies in the middle, with the wood 
all round it. The arrangements in leaves correspond 
with those in stems. If the leaf is held erect, with the 
upper surface next the stem, that surface is nearer the ` 
centre of the stem, and the lower surface is further 
from it. In accordance with this, the Wood-vessels of 
each bundle are usually nearer the upper surface, and 
the bast nearer the lower surface of the leaf. In roots 
the earliest bundles to appear (called the primary wood- 
bundles), consist entirely of Wood-vessels, which are 
formed successively nearer and nearer the centre of 
the root, increasing in size as they come nearer to the 
centre. Between them, and at the same distance from 
the centre as they are, the bast is formed; hence, the 
root is markedly different from the stem in the 
arrangements of the bundles. In the stems and roots of 
Monocotyledons, the bundles early assume the appearance 
and structure that they permanently retain; but in woody. 
Dicotyledons and Conifers, changes occur after the first 
year of growth, which greatly affect their original ap- 
pearance. In each bundle in the stem, the wood and 
the bast are separated by a layer of thin-walled cells ` 
(the “ cambium”) which continues to form new cells by — 
divisions parallel to its surfaces, producing new wood 
to the outside of the older wood, and new bast to the 
inside of the older bast. The cambium forms a complete 
cylinder around the wood of the stems of these plants, 
and gives origin to ring above ring of wood, usually one 
in each year of growth. The bundles grow so large that 
they are separated only by narrow belts of cells (medullary 
rays), the oldest of which runs from the pith in the 
centre to the cortex outside the bast; while the new 
rays formed each year run from the inner border of the 
ring of wood to the cortex. The fibro-vascular bundles 
can scarcely be separated, after a time, from one another; 
but the wood and the bast are easily disunited in most 
Dicotyledons at the cambium, as the cells of this ring 
readily give way, and the bark is thus easily separable 
from the wood. The bast forms the innermost layer 
of the bark, and its connection with the wood tends 
to become less evident than it was before the bundles 
were united by the continuous cambium. 
In the roots of Dicotyledons and Conifers, the earliest- 
formed wood-bundles do not grow; but there is a layer 
of cambium to the inside of each bast bundle, and soon 
this layer begins to form wood from its inner surface, 
and bast from its outer. After a short time, the cam- 
bium forms a continuous layer like that in the stem, 
and the roots in cross-sections look much like stems, 
except that the pith in the centre is often small or 
wanting, and that a practised eye can usually detect 
the primary wood-bundles lying close to the centre, and 
free from the bundles formed by the cambium. 
We must now pass to the various kinds of Vessels 
met with in the wood and the bast. In the wood of all 
