長柄菊

目： 菊目 Asterales

科： 菊科 Asteraceae

屬： 羽芒菊屬 Tridax

種： 長柄菊 T. procumbens

Distribution:

Native to southern Mexico, it originates from most parts of Central and South America, the Galapagos Islands, and the Caribbean.
Known introduced regions: It has naturalized in Africa, East Asia, the Pacific region, and Australia.
In Taiwan: Found along roadsides, in wastelands, and vacant lots in the central and southern coastal regions, it has gradually spread to eastern and northern areas.

Roots:

Long-stalked chrysanthemum has a prominent taproot, from which lateral roots branch out. The taproot is usually thick, and the lateral and fibrous roots are widely distributed, capable of penetrating deep into the soil. It adapts well to various soil environments and performs best in well-drained soils.

Stem:

Perennial prostrate herb, with slender stems that often produce numerous adventitious roots at the nodes. The stems are about 30-100 cm long, the base about 0.3 cm in diameter, slightly quadrangular, and branched, with internodes 0.4-0.9 cm long.

Leaves:

The basal leaves are somewhat smaller, while the middle leaves have petioles up to 1 cm long, rarely 2-3 cm. The leaf blades are lanceolate or ovate-lanceolate, 4-8 cm long and 2-3 cm wide, tapering or nearly wedge-shaped at the base, with a lanceolate acuminate tip. The margins have irregular coarse and fine teeth, often shallowly lobed near the base, with 1-2 pairs of lobes or sometimes only on one side of the leaf edge. The upper leaves are smaller, ovate-lanceolate to narrow-lanceolate, with short petioles, 2-3 cm long and 0.6-1.5 cm wide, nearly wedge-shaped at the base, with a short pointed to acuminate tip, and coarse teeth or shallow lobes near the base.

Flowers:

Few capitula, solitary at the tops of stems and branches; peduncles 10-20 cm long, rarely up to 30 cm, sparsely hairy, denser below the inflorescence; involucre bell-shaped, 0.7-0.9 cm long; phyllaries in 2-3 layers, the outer green, ovate or ovate-oblong, 0.6-0.7 cm long, with short or slightly pointed tips, densely hairy on the back, the inner oblong, 0.7-0.8 cm long, hairless, receptacle slightly elevated, palea about 0.8 cm long, with awn-tipped or nearly pointed tips.
Many bisexual flowers, with tubular corollas about 0.7 cm long, covered with short soft hairs, slightly larger at the top.Flowering period: November to the following March.

Fruits:

Seeds:

Oval or egg-shaped, small and flat. The surface typically has small protrusions or textures, helping to anchor and absorb water in the soil. The seeds have strong reproductive ability and germinate easily in suitable environments.

Uses:

In Taiwanese folk medicine, long-stalked chrysanthemum is commonly used to treat pneumonia. The whole plant has the effects of clearing heat, detoxifying, reducing dampness, and reducing swelling. It can treat pneumonia, hepatitis, hypertension, and difficulty urinating. The essential oil extracted from long-stalked chrysanthemum has repellent and insecticidal effects on common insects such as houseflies, ants, mosquitoes, stink bugs, and cockroaches.

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