Helianthus annuus commonly known as Common sunflower. It is a member of the Asteraceae family. Sunflowers are mainly grown for their properties. They are grown in gardens for decoration and their seeds are also roasted and eaten. Oil is also extracted from sunflowers which is used in cooking food. In this article, we will learn about the position of leaves, flowers, and fruits of Sunflower.
Scientific Name: Helianthus annuus
Some Basic Information about Helianthus annuus
Habit– An annual herb.
Root– Tap root.
Stem– Erect, solid, branched, cylindrical, hairy.
Leaf– Simple, alternate, petiolate, exstipulate, ovate, dentate margin, acute apex, unicostate, reticulate venation.
Inflorescence– Head or capitulum, (peduncle is flat on which florets are attached) with prominent involucre of bracts, heterogamous flowers.
(a) Ray Floret– Arranged on the periphery of capitulum, ligulate, incomplete, unisexual, zygomorphic, epigynous.
Calyx– Sepals 5, in the form of pappus.
Corolla– Petals 5, gamopetalous, strap-shaped, valvate aestivation, yellow.
Androecium– Absent.
Gynoecium– Bicarpellary, syncarpous, inferior ovary, unilocular, only one ovule, basal placentation, style long, stigma bifid.
Floral formula: Br% ⚥ K5 Pappus C(5) A0 G(2)
(b) Disc Floret– Arranged in the central part of the capitulum, tubular, bracteate, actinomorphic, hermaphrodite, complete, epigynous.
Calyx– 5, in the form of pappus.
Corolla– Petals 5, gamopetalous, tubular, valvate aestivation.
Androecium– Stamens 5, syngenesious, epipetalous, anthers dithecous, basifixed, introrse.
Gynoecium– As in ray floret.
Fruit– Cypsela.
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Floral formula-Br ⊕ ⚥ K5 Pappus C(5) A(5) G (2)
Systematic Position:
Division – Phanerogamia
Subdivision – Angiospermae
Class – Dicotyledonae
Subclass – Gamopetalae
Series – Inferae
Order – Asterales
Family – Asteraceae
Genus – Helianthus
Species – annuus
