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| Cosmos bipinnatus | |
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Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Cosmos |
| Species: | C. bipinnatus |
| Binomial name | |
| Cosmos bipinnatus Cav., 1791 | |
| Synonyms[1] | |
Synonymy
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Cosmos bipinnatus, commonly called thegarden cosmos,Mexican aster[2] orcosmea,[3] is a medium-sized floweringherbaceous plant in the daisyfamily Asteraceae,native to the Americas. Thespecies and itsvarieties andcultivars are popular asornamental plants intemperate climate gardens.[4][5][6][7]
Cosmos bipinnatus is anannual that is often consideredhalf-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, roughtrichomes, but some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, and sometimes the leaves are almostsessile.
The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage appears as if finely cut into threadlike segments. When flowering, the plants can become top heavy. This problem is alleviated when they are grown in groups, as the bipinnate leaves interlock and the plants support each other.[8]
Theachenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronouncedrostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. Apappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.[9]
The very conspicuous cup-shapedinflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded bybracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip isciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, with a yellow line.
The mostly eight rayflorets are pink to violet or white colored, at the base may show noticeable stains caused byanthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.[10]
According toPlants of the World Online this plant is native to Mexico.[11] However, other sources list it as native to the United States and Canada.[12] Since it is used as an ornamental plant in many countries and prone to sedimentation[clarification needed], it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America,South America,the West Indies,Italy,Australia, andAsia, where it is a garden escape (introduced species) and in some habitats becoming aweed.[8]
Cultivars ofCosmos bipinnatus in cultivation today are listed here. Those markedagm have gained theRoyal Horticultural Society'sAward of Garden Merit.
Growth characteristics of this plant include:
Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage.Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs andaphids have a taste forCosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).[28]
The flowers ofCosmos bipinnatus attract birds and butterflies,[28] including themonarch butterfly. It can be part ofbutterfly gardening and pollinator/honey-beehabitat gardens.[28]
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