Tail. — The Tail, Cauda , is an elongated and feather-like appen- 
dage surmounting the apex of the seed, but formed 
of the persistent style, as in Clematis. 
Taxonomy. — This Greek compound is by some writers made 
use of to denote that department of Botany in which 
plants are classified, or arranged into a system. 
Tendril. — The tendril is a thread-shaped and generally 
spiral process issuing from the stem, branch, or 
petiole, and sometimes even from the expansion of the 
leaf itself : being an organ by which plants of weak 
and climbing stems attach themselves to other plants, 
or to other substances for support, and being always 
much stronger than a branch of the same size. In 
attaching itself to its supporter, it generally twists it- 
self round, till it has taken so many circumvolutions, 
as to make its hold secure. But what is very singular 
is, that there are some plants, as Bryonia, whose ten- 
drils, after performing a certain number of circumvo- 
lutions in one direction, twist themselves about spon- 
taneously, and perform their future circumvolutions in 
a contrary direction. But all tendrils do not twist 
round their supporter. Those of Vitis hederacea, the 
Virginian creeper, terminate ultimately in a flat and 
fleshy process, by which they can attach themselves, in 
default of better support, even to the surface of a brick 
or stone wall. 
Tepals. — 1 The parts or divisions of a perianth, strictly so called 
are tepals. Thus the perianth of the Tulip, is six- 
tepalled, first green, and then becoming coloured. 
Tergeminate. — When a compound leaf resembles the bigemi- 
nate in its foot-stalk divisions, and has besides, a third 
pair of leaflets, at the point where the secondary leaf- 
stalks originate. 
Terminal. — Applied to parts, when they are at the end of a 
branch or stem. 
Ternate. — When leaves stand by threes round the stem. 
Testa. — This term was employed by Gasrtner, to denote the 
outer coat of the seed. It is equivalent to the primine 
of Mirbel. 
Thalamus — The receptacle of the flower is sometimes denomi- 
nated the thalamus, or torus, or clinium. 
Thallus — The frond of Cryptogam ous plants that bears the 
fructification, whether by seeds or sporules, is denomi- 
nated the thallus. 
Theca. — The theca is the urn or capsule, that contains the 
seeds or sporules of the mosses. 
Thorn. — The thorn is a species of armature, originating in the 
wood, being an abortive and: indurated bud, and ex- 
emplified in the genus Mimosa, or Crataegus; the for- 
mer presenting in some of its species, a host of spears, 
that is, impenetrable even to the rhinoceros ; and the 
latter, a barrier sufficiently formidable to prevent the 
incursions of cattle, as in our Quicksets. 
Thyrse.— The Thyrse, is a species of inflorescence, being an 
assemblage of flowers supported upon a primary pe- 
duncle, subdivided as in the branching panicle; but 
differing from it in having the lower or partial pe- 
duncles longer and placed in a horizontal or expand- 
ing direction ; and the upper ones shorter and more 
erect. It is exemplified in Syringa vulgaris, and in 
the Vine. 
Tomentose. — Covered with a downy pubescence- 
Trichotomous. — Divided into three branches. 
Tricuspid. — Terminating in three rigid spines. 
Trifid. — Three-cleft. 
Tripartite. — A laciniated leaf divided into three parts. 
Tripinnate. — In a compound leaf when along the sides of a 
common petiole, there are secondary footstalks sup- 
porting a ternary set, which are pinnate. 
Trowel-si-iaped. — (Deltoid) When a leaf has three angles, 
and represents the Greek letter Delta. 
Truncated. — If a root bears the appearance of a fusiform 
root, suddenly cut off, it is then termed a truncated 
or bitten root. 
Trunk. — The trunk, or caudex ascendens of Linnaeus, is that 
part of the plant which springs immediately from the 
root, and ascends in a vertical position above the sur- 
face of the soil, supporting the branches, and consti- 
tuting for the most part the principal bulk of the in- 
dividual. It is a term taken from the Latin truncus, 
and has the same signification among botanists which 
it had among the ancient classics. 
Tube. — The lower part of a monopetalous corolla, being gene- 
rally of a cylindrical form, is by botanists denomi- 
nated the tube. 
Tuberous Root. — Some roots are tuberous that is, giving 
origin to a tuber or tubercle, or, as botanists now call 
it, a subterranean stem, or to several such stems 
united in a cluster. If the tuber is single, it is gene- 
rally solid, as in Bunium Bulbocastanum. If the tu- 
bers are not single, they are often in pairs, as in Or- 
chis mascula or early Orchis. 
Tubular. — Approaching very near in figure to the campanu- 
late, like the flower of Digitalis purpurea. 
Tuft- — The tuft is a hair-like or plume-like substance, form- 
ing the appendage of some seeds, as that of Epilobium 
and Asclepias. 
Tumours. — Tumours are irregular enlargements of the organs 
of the vegetable, disfiguring, but not always injuring, 
the plant. 
Twining Stem. — The twining stem is a stem that ascends its 
prop spirally and uniformly, in direction either from 
right to left, or the contrary, and never otherwise. 
[See the article Stem.] 
Umbel. — The umbel is a mode of flowering, in which a num- 
ber of flower-stalks issuing from a common centre, 
diverge like the rays of an umbrella, bearing their flowers 
on the summit, and raising them to about the same 
height. The Carrot, Parsnip, and common Hemlock 
are familiar examples. If the rays of the Umbel are 
undivided, so that an individual ray supports but a 
single flower, as in Hydrocotyle, the Umbel is said to 
be simple. But if rays of the primary Umbel are 
themselves subdivided, so as to form and support se- 
condary Umbels, as in Heracleuin, and most umbel- 
late plants, the Umbel is then said to be compound. 
It is terminal, as in the Carrot, or lateral, as in Cau- 
calis nodiflora. 
Umbilicus. — The Umbilicus is merely another term for the 
hilum or scar, which is occasioned by the fracture of 
the umbilical cord. 
Umbilical Cord. — The thread-like process by which’ some 
seeds are attached to the placenta, is the umbilical 
cord, already described in the article Funiculus. 
Unarmed.— Devoid of spines or thorns. 
Uncinate. — Curved like a hook. 
Undershrub. — Undershrubs are plants, perishing either 
wholly or in part ; but sometimes surviving by their 
woody parts for more than one year, as Tree Mignonette. 
Undulated. — Margins waved obtusely up and down. 
Unequal. — Having two halves of unequal size. 
Unguis. — The Unguis is merely the Latin term for that part 
of a petal which we have already defined under the 
head of the article Claw. 
Utricle. — The Utricle is a small bladder, like capsules, con- 
sisting of one cell and one seed. Gmrtner exem- 
plifies it in Chenopodium and Clematis, in which Sir 
J. E. Smith seems to regard it as being merely cuticle. 
Valves. — The several distinct pieces into which the pericarp 
spontaneously separates, when the fruit is ripe, are de- 
nominated valves. All pericarps do not open in the 
same manner, but all individuals of the same species 
open in the same manner ; and the persistent axis 
from which they separate is called the columella. 
