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Floral anatomy of Actinomeris squarrosaand Bidens biternata(Asteraceae)

Singh, B. P. and Agarwal, A. (2001) Floral anatomy of Actinomeris squarrosaand Bidens biternata(Asteraceae). Acta Botanica Hungarica, 43 (3-4). pp. 423-432. ISSN 0236-6495

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Abstract

Floral anatomy of Actinomeris squarrosaand Bidens biternatahave been described. The presence of pappus is an important structural feature of the Asteraceae. It has been considered by some as phyllome and by others a trichome structure. The presence of vascular supply to the pappus scales shows that it is a phyllome structure. Once the pappus is considered as a phyllome structure, two major lines of specialization can be established in this family from a primitive type of five vascular scales. In ome line of evolution there has been increase in the number of pappus from five to twenty and finally indefinite in number and the vascular supply is totally suppressed. In another line of evolution there has been a reduction in the number of pappus scales from five to two and finally total reduction of the scales. The disc-florets of Bidens biternataare pentamerous but occasionally tetramerous florets are also observed. In Actinomeris squarrosa disc-florets are tetramerous florets are derived from pentamerous floret by complete fusion of the two anterior alternipetalous strands is discussed. In the Asteraceae, the pistillate ray florets are derived from disc florets by formation of a deep sinus in the corolla on the posterior side, followed by gradual suppression of the androecium. The neutral ray-florets are derived from ray-florets by complete reduction of an ovule, loculus and style along with its vascular supply is also discussed.

Item Type: Article
Subjects: Q Science / természettudomány > QK Botany / növénytan
Depositing User: Endre Sarvay
Date Deposited: 11 Mar 2018 14:52
Last Modified: 11 Mar 2018 14:52
URI: http://real.mtak.hu/id/eprint/77956

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