h, and the Hornbeam, retain
their leaves to a late period of autumn?

Because the life of the twigs on which they grow is not sufficiently
vigorous to throw them off, after the brown colour indicates that they
are dead.

Why have some plants been termed the Poor Man's Weather-glass?

Because they shut up their flowers against the approach of rain.
Linnaeus, however, thinks, that flowers lose their fine sensibility,
after the anthers have performed their office, or when deprived of
them artificially. Sir James Smith also observes, that some species
are sometimes exhausted by continued wet; "and it is evident that
very sudden thunder showers often take such flowers by surprise, the
previous state of the atmosphere not having been such as to give them
due warning."

Many flowers have a regular time of opening and shutting. We have
already mentioned the Marigold; the goat's-beard is vulgarly called
"John go-to-bed at noon," from its closing at mid-day; and at the Cape
of Good Hope there is a "four o'clock flower," because it invariably
closes at that time. The common daisy is, however, a readier example,
its name being a compound of day's and eye--Day's-eye, in which
way, indeed, it is written by Ben Johnson. It regularly shuts after
sun-set, to expand again with the morning light. Thus,--

The little dazie, that at evening closes.

Spenser.

By a daisy, whose leaves spread,
Shut when Titian goes to bed.--_G. Withers._

Leyden sings of moist or rainy weather foretold by daisies. Thus we
may examine a whole field, and not find a daisy open, except such as
have their flowering nearly over, and have in consequence lost their
sensibility.

The daisy is one of the pet flowers of the poets. Chaucer is ecstatic
in its praise, and calls it his "owne hartes' rest;" Burns, "Wee,
modest, crimson-tipped flower;" and Wordsworth, in beautiful and
touching simplicity, has addressed several poems to "the poet's
darling."

Appended to Richard's valuable "Elements," is the _Horologium Florae,_
(timepiece of Flora,) or a table of the hours at which certain plants
expand and shut, at Upsal, 60 deg. north latitude. The earliest Meadow
Salsafy opens from 3 to 4 A.M.; and closes from 9 to 10 A.M. The
latest A.M. is the _Mesembryanthemum Modiflorum,_ (used in the
manufacture of Maroquin leather,) which opens 10 to 11 A.M.,
and closes at 12 P.M. The latest opening P.M. is the _Cactus
Grandiflorus,_ 9 to 10 P.M., and closing at