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闇之眼 發問時間: 社會與文化語言 · 9 年前


Leaves located in association with flowers are frequently modifiedor reduced in size relative to vegetative leaves on the same plant. Such leavesare referred to as bracts (or hypsophylls; cf. cataphylls, 88). Any leaf,modified or not, that subtends a flower can be termed a bract, although thereare many instances in which flower buds are found without associated subtendingleaves. Conversely, the stalk (pedicel) of an individual flower may bear a leaf(typically, one in monocotyledons and two in dicotyledons, ) that may or notsubtend its own flower. Such a leaf is termed a bracteole. Thus, the bracteoleof one flower may be the bract of another flower. If a number offlowers are borne in a condensed inflorescence, their individual bracts willoccur in a tight whorl or involucres. However, an involucre may beassociated with a single flower. A compound umbel may display an involucreof bracts at its base and an involucel beneath each distal flower cluster. Bracteolesare often inconspicuous but nevertheless can protect very young and developingflowers (Prenner 2004). The protective bracteoles of Macaranga hullettii carry extrafloral nectarines on their adaxialsurfaces and form domatia (244) containing thrip colonies, which are implicatedin pollination (Moog et al. 2002). Each individual bract of an involucre can becalled a phyllary. One or several of the bracts associated with an inflorescencemay be relatively large and conspicuous (84,85E, 86A, 86B, 392A) and may act toattract pollinators. Large bracts may assist in the wind dispersal of fruit or fruits(279E). Bracts are a conspicuous feature of many monocotyledonousinflorescences) and form distinctive features of the grass spikelet.Generally, bracts may appear leaf-like, are frequently scale-like, may bemassive as in many palms, or may be modified into spines , hooks (197B),or persistent woody structures surrounding fruits (193H; such as the fusedwoody bracts, the cupule, of oak).

1 個解答

  • 9 年前

    協會位於花與葉子經常 modifiedor對同一植物營養的葉大小相對減少。這種 leavesare稱為苞片(或hypsophylls;比照cataphylls88)。任何葉,修改或不subtends一朵花,可稱為苞片,雖然 thereare許多實例中,發現無關聯 subtendingleaves花蕾。相反,一個人花的莖(花柄)可承受葉(通常情況下,在單子葉植物和雙子葉植物),可能會或notsubtend自己的花。這樣一個葉子被稱為苞片。因此,“bracteoleof一花可能是另一朵花的苞片。如果一個數字 offlowers是一個濃縮的花序承擔的,他們的個人苞片緊螺紋或involucres willoccur。但是,苞可能與一花獨放beassociated。複合繖形花序,可能會顯示在其基地和involucel每個遠端的花簇之下involucreof苞片。

    Bracteolesare往往不起眼,但可以保護很年輕,developingflowers(Prenner2004年)。 Macaranga hullettii保護苞片進行 extrafloral油桃adaxialsurfaces和形式domatia(244)包含thrip殖民地,這是implicatedin授粉(穆格等,2002)。個人的每一個苞苞片becalled總苞片。 inflorescencemay相關的苞片中的一個或多個比較大和突出(84,85Ë,86A,86B,392A),並可能作為 toattract授粉者。大苞片,可能有助於在風散佈的水果或水果(279E)。苞片顯著特點是許多 monocotyledonousinflorescences),形成特色鮮明的基層 spikelet.Generally,苞片,可能會出現葉片狀,經常鱗片狀,可能會 bemassive在許多棕櫚樹,或可能修改成刺,鉤(197B ),或持久木質結構周圍的水果(193H;如fusedwoody苞片,吸盤橡木)。





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