Sunflower

Sunflower

Scientific name: Helienthus anus L.

Local/Bangla name: “Surjamukhi”

Taxonomic Position According to Cronquist System (1988)

Botanical Description of Sunflower

Habit: annual herb

Fig. A Sunflower Field

Root: Usually tap roots but roots modified into tubers.

Stem: Erect or prostate, rarely climbing, some time woody

Fig. A whole plant of sunflower

Leaf: Simple some time compound

Flower: Inflorescence head or capitulate

Fig. Inflorescence (Head/capitulum) of Sunflower

Involucre bract: The head or capitulum are surrounded by a whorl of bracts called the involecre thus producing a flower cluster resembling a single flower.

Pappus: Sepalsare modified into threadlike, hairy, or bristly structures, which surround the fruit and can stick to animal fur or be lifted by wind, aiding in seed dispersal.

Two types of flowers are present i.e. ray floret and disc floret

Ray floret-Present in the periphery, zygomorphic, ligulate, unisexual female flowers

Disc floret: Central position, bisexual, actinomorphic

Fig. Ray and Disc Florets of Sunflower

Calyx: Calyx is modified into pappus or scale leaf

Corolla: Petal 5 or three tubular in disc florets or ligulate in ray florets, gamopetalous,aestivation is valvate.

Ray floret-unisexual, pistillate or neuter, zygomorphic, incomplete, sessile

Calyx-modified into pappus,

Corolla:Petal 5, rarely 4, ligulate, aestivation valvate.

Androecium:Absent.

Gynoecium-Carpel2, syncarpous, monocarpellary, ovary inferior, placentation basal.

Disc floret-Bisexual, complete, actinomorphic, sessile

Calyx: Sepal converted into pappus

Corolla-Petal 5, gamopetalous, tubular, aestivation valvate.

Androecium: Stamen 5, syngenesious, epipetalous

Gynoecium: Bicarpellary,syncarpous, ovary inferior with single locule, stigma two and bifid

Economic Importance

• Used as edible oil
• Used as ornamental plant
• Has medicinal virtue

Table 1. Sunflower Variety Developed by Bangladesh Agricultural Research Institute, Joydebpur, Bangladesh