486 TRELLIS. 
June and July; and the yellowish-white clover, 
T. ochroleucum, the cow-grass clover, 7. medium, 
and the common red clover, 7’. pratense, described 
in the article Cover. The three indigens of 
the third subgenus are the suffocated trefoil, 7. 
suffocatum, a trailing weedy annual of the sea- 
shores of England, about 6 inches in height, car- 
rying white flowers in June and July; the 
cluster-headed trefoil, 7. glomeratum, a trailing 
weedy annual of the pastures of England, about 
6 inches in height, carrying pink flowers in 
June; and the common white clover, 7. repens, 
described in the article Crover. The two indi- 
gens of the fourth subgenus are the strawberry- 
bearing trefoil, 7’. fragiferum, a creeping and 
somewhat agricultural perennial of moist pas- 
tures in England, about 3 or 4 inches high, car- 
rying flesh-coloured flowers in July and August ; 
and the subterraneous trefoil, 7. subterraneum, 
an erect handsome annual of the barren heaths 
of England, about 6 inches high, carrying 
white flowers in May. And the three indi- 
gens of the sixth subgenus are the procum- 
bent hop trefoil, 7. procumbens, the lesser yel- 
low trefoil, 7. minus, and the thread -shaped 
trefoil, 7. filiforme, all described in the article 
CLOVER. 
TREFOIL (Birp’s-Foot). See Brrn’s- Foor 
TREFOIL. 
TREFOIL (Marsh). See Bucksran. 
TREFOIL-SHRUB. See Prenea. 
TREFOIL-TREE. See Cyrrsus. 
TRELLIS. A contrivance of the nature of a 
lattice for supporting the branches of fruit-trees, 
or for training and supporting the stem and 
ramifications of ornamental climbing plants. The 
old-fashioned trellis for fruit-trees, or common 
wall-fruit trellis, is constructed upon a piered 
wall, and extends from the inside of one pier to 
the nearest inside of the next, and is closely 
similar in at once form, uses, and management 
to an espalier, and may be diversified, in its 
aggregate size and outline, and in the materials, 
dimensions, and arrangement of its rails, to suit 
the wants of different kinds of trees. See the 
article Espanier. The ornamental trellis of the 
flower-garden, particularly in its newest forms 
and applications, is endlessly diversified in shape 
and size, and admits of a considerable choice of 
material, and may be worked into great com- 
plexity of compound form, and affords a very 
wide scope for the combined exercise and display 
of ingenuity, fancy, caprice, and both good and 
bad taste. Some kinds of it are mimic and 
belong only to the greenhouse, while others are 
gigantic and belong to the open ground; and 
some are chaste and elegant, and serve only to 
exhibit the plants upon them to the best advan- 
tage, while others are stalking and fantastic, 
and fix enlightened attention only on their own 
absurdity. Ornamental trellises, on the whole, 
give gardens an excessively artificial or down- 
right harlequin appearance; and would have 
TRENCHING. | 
formed a far fitter accompaniment to the clip- 
ping and figuring horticulture of a former period 
than to the natural and flowing style of the pre- 
sent day. ‘The more we look on the present 
unnatural-looking shields for our climbing plants, 
the greater appears the necessity of an altera- 
tion. Whatever is unnatural in plant-growing, 
must have some great advantage to enable us to 
tolerate it at all. This may be said against 
plants growing in pots instead of the ground, for 
nothing but the necessity of doing so justifies it. 
Plants must be moved about, and therefore 
something to grow in is necessary, and that 
something is a pot or tub, or some receptacle for 
the soil they require. But in all cases, the nearer 
we can approach to familiar objects in our mode 
of training the better. There can hardly be a 
better guide than nature in all this. Where do | 
we find climbing plants?) Twining up and round 
pillars, insinuating themselves into all the cre- 
vices of a ruin, festooning the Gothic arch and 
the glassless window, enfolding the aged tree, | 
and clinging to the ancient gateway. All these | 
things can, more or less, be imitated. A pillar, 
whether broken or perfect, is not only an appro- 
priate, but a handsome design for a climbing 
plant. An ancient arched window is well | 
adapted for one of the larger kinds of plants; and 
there is one great advantage in such subjects, if 
well made they look better for not being entirely 
covered.” st 
TREMANDREA. See Terraruzca. | 
TRENCH. A long cut in the ground,—either 
a single spade-cut in the process of spade-tillage, 
or a mere furrow-cut for the purpose of draining, 
or a deep and wide ditch for the purpose of mi- 
litary defence. 
TRENCHING. Digging up the subsoil in the 
process of garden tillage or of spade husbandry. 
It admits of many degrees and variations ; and 
comprises any depth and amount of interference 
with the subsoil, from the simple stirring of it 
and bringing up merely an inch or two, to the 
complete upturning of a considerable stratum 
of it and bringing up the whole of this to the 
surface. It serves, in all its varieties, to reno- 
vate the soil, to imperviate the subsoil, to deepen 
the range and scope of roots, to improve the 
drainage, to increase the interior circulation of 
air and moisture, and to promote all the diges- 
tional chemical processes which prepare the 
mineral and gaseous food within the soil for ab- 
sorption by plants; and it must be adapted, in 
its particular depth and manner, to the charac- 
ter and circumstances of the particular ground 
on which it is performed, and by no means done 
everywhere and indiscriminately in the ordinary 
manner of making the top-spit and the bottom- 
spit of land simply interchange places,—a man- 
ner which is suited chiefly to a very deep homo- 
geneous garden soil which has been long in culti- 
vation. The trenching of all land whose subsoil 
differs materially from its soil—and especially of 
