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I QO PHARMACEUTICAL BOTANY
Polyadelphous, when there are several sets or branched bundles.
Syngenesious , when the anthers cohere. Example: Composites.
Color of Stamens. In most species the color of these organs is
seldom pronounced owing to their delicate structure. It varies
from greenish-yellow to yellow to white, through pink, pinkish-red,
red, purple, purple-blue to blue. It is yellow, for instance, in Sassa-
fras, Cucumber and Golden Club; greenish-yellow, yellow to red, in
Maples; yellow-pink to pink and pinkish-red, in some Mallows; in
Azalea amena the filaments are crimson-purple and the anthers, pur-
ple-blue; in the genus Scilla both filaments and anthers are blue.
Gross Structure and Histology of the Filament. The filament
may be cylindric as in the Rose, awl-shaped as in Tulip, flat and with
a dilated base as in the Harebell, three-toothed as in Garlic, appen-
diculate, when it bears an appendage as in Chatostoma, Alyssum, etc.
The filament is covered with a protective epidermis containing
stomata. Beneath this is a soft, loose cellular tissue, the mesophyll,
and in the center a small vascular bundle, the pathway of food from
the floral axis to the Cardizem 180 anther. In some cases the single bundle may Cardizem 180
split into two or three bundle parts.
Gross Structure and Histology of the Anther. Each staminal leaf
(microsporophyll) bears a special development or appendage as a
rule on its extremity which is Cardizem 180 the anther or microsorus. This consists,
fundamentally, of a median prolongation of the filament equal to the
connective or Cardizem 180 placenta. This develops on either side a quantity of
indusial tissue that grows out to form a covering substance that
protects and carries two microsporangia on either side. An anther
therefore consist of a median connectine or placenta, producing on
either side two anther lobes or indusial expansions. Each anther lobe
encloses two pollen sacs or microsporangia, which, in some cases,
remain distinct up to the dehiscence (splitting open) of the anther.
Thus in Butomus, the anthers show four pollen chambers up to the
time of dehiscence. Again in various species of Lauracece, the
anthers remain four lobed and dehisce by four recurved lids. But in
the great majority of Angiosperms each pair of pollen sacs fuse before
dehiscence, owing to the breaking down of the partition- between
them, and so, at that time, show two-celled anthers. Still more
PLANT ORGANS AND ORGANISMS 1 91
rarely the anthers may be two-celled in their young state and by the
breaking down of the partition become one-celled, Cardizem 180 e.g., Malvacea,
Externally the mature anther is bounded by an exothecium or epi-
dermis, often swollen, where lines of dehiscence occur, which may
develop stomata, also hairs. Within it is a combined layer or set of
one to often two or three, sometimes five or six cell layers (Agave,
etc.). of indusial and sporangial cells, the endothecium. Cardizem 180 The outer-
most one to three layers of this become spirally, annularly or stel-
lately thickened to form the elastic tissue of the anther, which, by
pressure against the delicate epidermis or exothecium, causes ulti-
mate rupture of the anther wall. Within the innermost endothecial
layer, bounding each sporangium, is the tapetum, a single-celled
layer. This, near the time of dehiscence, undergoes breaking down
or absorption by developing pollen or microspore cells. Filling the
cavities of the four sporangia are the mature pollen grains. The
connective shows in or near its center a vascular bundle with xylem
uppermost and phloem downward, surrounded by thin-walled cellu-
lar tissue, from which the indusial and sporangial substance has
matured by extension.
Anther Dehiscence. This Cardizem 180 is the breaking open of the anther to
discharge the pollen.
When fully ripe the dividing partition between each pair of spor-
angia usually becomes thinned, flattened and ultimately breaks down,
while the elastic and resistant endothecium, steadily pushing against
the more delicate and now shrinking exothecium causes rupture
where endothecium is absent, namely along opposite lines of the
anther wall. Thus arises a line of anther dehiscence called longi-
tudinal anther dehiscence on either side of the anther sacs. In the
.division Solanece of the family Solanacecz which includes Belladonna,
in some of the Ericacece as Rhododendron and Azalea, etc., the
anthers dehisce by small apical pores from which the pollen is shed.
This kind of dehiscence is called apical porous dehiscence. Again,
in Lauracece and Berberidacecz, the anthers dehisce by recurved valves.
This is called valvular dehiscence.
Moreover, in Malvacea the originally longitudinal anther is divided
internally by a partition. It gradually swings on the filament so
that eventually the anther is transverse and the partition becomes
I Q2 PHARMACEUTICAL BOTANY
absorbed, thus becoming a one-celled anther with transverse dehis-
cence. in its mature state.
Development of the Anther. Each stamen originates as a knob-
like swelling from the receptacle between the petals and carpels.
This swelling represents mainly future soral (anther) tissue. The
filament develops later. When such a young sorus or anther is cut
PIG. 95. Cross-section of a mature lily anther. The pairs of pollen chambers
unite to form two pollen sacs, filled with pollen grains; s, modified epidermal cells
at line of splitting. (From a Text-book of Botany by Coulter, Barnes, and Cowles.
Copyrightjoy the American Book Company, Publishers.)
across and examined microscopically, it shows a mass of nearly simi-
lar cellular tissue in which the first observable Cardizem 180 changes are the
The surface dermatogen cells become somewhat flattened and regu-
lar to form the future epidermis or exothecium of the anther. About
the same time some cells, by more rapid division in the middle
of the anther substance, give rise to the elements of the Cardizem 180 vascular
bundle in the connective. Then, along four longitudinal tracts,
rows of cells remain undivided Cardizem 180 or only divide slowly as they increase
in size and around them cells divide and redivide to form the future
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