In Botanical, a bractée is a floral Pièce in form of Feuille belonging to the Inflorescence. Intermediary between the sheet and the Fleur, bractée is often similar to a sheet (one speaks then about “bractée foliaceous”), but it can also resemble a flower or a petal of flower, in particular by its colors. Many bractées, known as membranous, have a particular, translucent consistency and coriace, and a color coppered, silver plated or gilded. It is this last characteristic which is at the origin of the name: in Latin, the term bractea (also written brattea ) indicates a metal sheeting indeed, in particular a gold sheet.
The role of bractées is not clearly defined. In much of case, one notices however that they play a protective part, similar to that of the sepals before the blossoming of the flowers (for example at the Astéracées, or Made up); in other cases, by their colors, they function like panels signalisateurs for the pollinating insects (frequent phenomenon at the Lamiacées).
Examples of bractées remarkable
The euphorbiums are plants not having neither petals, nor sepals. Their inflorescence, called cyathe, is made of a female flower surrounded by some male flowers and Glandes nectarifères. All these elements rest on a couple of bractées forming a kind of cut. Bractées are very often similar to the sheets by their form, but they are characterized some by their color, generally drawing on the yellow. They can also be round whereas the sheets are oblong.
- Lavender stoechas: the inflorescence of this Lavender, just like that of Lavandula dentata , is a kind of ear finished by a small bouquet of bractées mauve or violets. It is obviously about a signal intended for the Abeille S and inviting them to come to pollinate the flower.
- green Sage: even thing with this other labiée ( Salvia viridis ), often planted in the gardens for its decorative side. The inflorescence, with small the enough flowers for a sage, ends in a whole series of bractées foliaceous violets, they also panel signalisator for bees. One also finds bractées coloured at the sclarée Sauge and several others labiées.
The limes, with the round or twisted green sheets, have inflorescences in cymes with long stalk. Each stalk carries at its bractée base one (and only one) oblong, more or less elliptic, in the shape of oar say some. This bractée yellow blanchâtre, membranous, remains in place until the winter. it is used, as well as the flowers, in the calming herb tea clothes industry.
The wild carrot ( Daucus carota L.) has the ombelles ones with many rays, each ray being finished by bractées, generally trefoil, surrounding ombelles and ombellules. After flowering, the rays and bractées are closed again, forming a kind of basket which maintains the fruits in driving position until their maturation. The inflorescence itself rests on long bractées cut out, they also trefoil, the very visible ones with the beginning of flowering.
Astéracées, or Composed, have a inflorescence in flowerhead. This flowerhead, often called unsuitable flower in way, is in fact a group of flowers, or florets, which are presented either in the form of strips (florets ligulas), or in the form of tubes (tubulés florets), or both at the same time. All these flowers are surrounded by an involucre of bractées sometimes thorny, in particular ensuring the protection of the flowerhead before the blossoming of the flowers. Some of these bractées are spectacular (Thistle-Marie), others are very familiar for us, since we consume them regularly.
- Artichoke: it is the case of artichoke, since the “sheets” whose we eat the tender end in fact of are bractées rather close to those of the thistles or the centauries. We consume artichokes at the time when the involucre is closed again on the flowerhead, before the blossoming of the flowers.
- Centauries: if one looks at capitulates it of a centaury, one realizes that the involucre is finally rather similar to that of an artichoke, but in smaller. Bractées, like the tiles of a roof, the ones on the others are inserted. They are frequently surrounded or finished by lashes or spines which often make it possible to the botanists to differentiate them. Some bractées carry long spines, for example the Centaurée of the solstice.
- Carline S: the carlines are ideal plants for the study of bractées, because they comprise three completely different lines of them. The bractées external ones are identical to the sheets, by their form and their color, but they are smaller. The bractées average ones are coriaces, woody, often very thorny. Finally bractées interior, the slightly membranous ones, with gilded or silver plated color, radiate around the floral disc and are easily taken for flowers similar to those of the daisies.
The amateurs of plants with bulbs or rhizomes (crocus, narcisses, iris) watch for each day the blossoming of their preferred flowers. Before the blossoming, the flowers or the inflorescences are protected by a kind of membrane more or less translucent, which opens then into two or three valves, sometimes only one. This membrane is it also one bractée, called spathe . After flowering, the spathes can be null and void or persistent. Among the most spectacular spathes, one will note those of garlics, entirely wrapping the ombelles ones, and of which some hang then like serpentines along the stem ( Allium oleraceum , Allium carinatum ). There will not be guard to forget largest of all, the spathes of the Aracées, large fleshy sheets wrapping the spadice. Lastly, the glumes and the glumelles ones of the Poacées (or graminaceous) are they also bractées.
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