Erigeron canadensis 小蓬草、加拿大蓬、飛蓬、小飛蓬*

Common name: Canadian Fleabane
Scientific name: Erigeron canadensis 小蓬草、加拿大蓬、飛蓬、小飛蓬*
Genus: Erigeron 飛蓬屬
Family: Asteraceae or Compositae 菊科, aster , daisy, composite or sunflower family

Remarks*: It was formerly named Conza canadensis 小蓬草、小白酒草, belonged to Conza 假蓬屬、白酒草屬. It was originally described as Erigeron by Linnaeus, transferred to Conyza by Cronquist based on specific floral traits (such as disk-to-ray floret ratios), where they stayed for a long time, then recently genetic and taxonomic revisions put back in Erigeron. It is also recorded in Hong Kong as an exotic plant.

Origin: Neophyte (established after 1500 AD). I It is a native of North America and has been known in the London area since 1690.

Date: 13th July (flowering) & 15th Aug (frutiing)

[3026] An annual tall, erect, much-branched yellowish-green annual, can reach up to 100cm (30-120cm). Stem erect, branched on upper portion.

[3016] Stem ridged and with hairs. Leaves alternate.

[3017] Lower stem also ridged and with hairs.

[3016] Enlarged photos to show the ridges and hairs along the stem.

Stem densely or loosely hirsute 粗毛的 or glabrous.

[3032] The base of the stem swollen a little bit. Basal leaves usually withered at flowering stage.

[3030] Stem leaves numerous, 3-12cm (3.5–10 cm × 2–6 mm), linear-lanceolate. 

[3027] Lower leaf. Leaf surfaces nearly glabrous. 

[3029] The underside of the leaf.

[3030] Long forward hairs on the leaf margin (bearing loose and distinct, curved and stiff hair along margin.)

[3025] Much-branched stem and the large pyramidal panicle 圓錐花序. (Stem branched on upper portion.)

[3023] The flower buds.

[3023] Side view of the flower buds of different stages.

[3015] Side view of flowers

[3015] Flower heads 3-5 mm across, white petals of the ray florets,  involucral bracts glabrous (Actually, it has a few hairs in this indvidual)

(vs heads 5-8 mm across, ray florets with brownish petals, involucral bracts densely hairy in Erigeron sumatrensis 蘇門白酒草、野茼蒿, Guernsey Fleabane)

(vs flower heads 7-11 mm across, flower head clearly red tipped, involucral bracts hairy in Erigeron bonariensis 香絲草、野茼蒿、美洲假蓬、野地黃菊、蓑衣草、消息草, Argentine fleabane)

(vs flower heads 3-5 mm across, flower head with tendency to purple tips, involucral bracts with few hairs in Erigeron floribunda 多花飛蓬、多花飛蓮, Bilbao fleabane) 

[3020]

[3021]

[3020] Marginal female ray florets white, ligulate, and yellow central bisexual disc florets that is 4-5 lobed.

[3022] Flower heads 3-5mm across. Ray florets more than 1 row.

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The following photos were taken on 15th Aug:

[5012] The flower head swollen at the base now....it may force it to split open to release the fruits afterwards.

[5021] Splitting open now, numerous pappus (white hairs) which is the modified calyx could now be seen. 

[5020] The fruits, achenes, are ready to be released.

[5020_1] Enlarged photo above to see the pappus radiates from the top of each achenes.