|A cotton tree seen here at Delhi with flowers which bloom from February to April|
Bombax ceiba, like other trees of the genus Bombax, is commonly known as cotton tree. More specifically, it is sometimes known as red silk-cotton; red cotton tree; or ambiguously as silk-cotton or kapok, both of which may also refer to Ceiba pentandra.
This Asian tropical tree has a straight tall trunk and its leaves are deciduous in winter. Red flowers with 5 petals appear in the spring before the new foliage. It produces a capsule which, when ripe, contains white fibres like cotton. Its trunk bears spikes to deter attacks by animals. Although its stout trunk suggests that it is useful for timber, its wood is too soft to be very useful.
Bombax ceiba grows to an average of 20 meters, with old trees up to 60 meters in wet tropical regions. The trunk and limb bear numerous conical spines particularly when young, but get eroded when older. The leaves are palmate with about 6 leaflets radiating from a central point (tip of petiole), an average of 7~10 centimeters wide, 13~15 centimeters in length. The leaf's long flexible petiole is up to 20 cm long.
Cup-shaped flowers solitary or clustered, axillary or sub-terminal, fascicles at or near the ends of the branches, when the tree is bare of leaves, an average of 7~11 centimeters wide, 14 centimeters in width, petels up to 12 centimeters in length, calyx is cup-shaped usually 3 lobed, an average of 3~5 centimeters in diameter. Staminal tube is short, more than 60 in 5 bundles. stigma is light red, up to nine centimeters in length, ovary is pink, 1.5~2 centimeters in length, with the skin of the ovary covered in white silky hair at 1mm long. Seeds are numerous, long, ovoid, black or gray in colour and packed in white cotton.
The fruit, which reaches an average of 13 centimeters in length, is light-green in color in immature fruits, brown in mature fruits.
The tree is widely planted in southeastern Asian countries (such as in Vietnam, Malaysia, Indonesia, southern China and Taiwan, etc.) According to Chinese historical record, the king of Nam Yuet (located in the southern China and northern Vietnam nowadays), Zhao Tuo, gave a tree to the emperor of the Han dynasty in the 2nd century BC.
This tree is commonly known as semal (Hindi: सेमल), shimul (Bengali: শিমুল) or ximolu (Assamese: শিমলু) in India. It is widely planted in parks and on roadsides there because of its beautiful red flowers which bloom in March/April. This tree is quite common in New Delhi although it doesn't reach its full size of 60m there because of the semi arid climate. The cotton fibers of this tree can be seen floating in the wind around the time of early May. This tree shows two marked growth sprints in India: in spring and during the monsoon months. Perhaps due to subtropical climate and heavy rainfalls, it's found in dense population throughout the Northeast India.
The 1889 book 'The Useful Native Plants of Australia records that the tree was at that time known as Bombax malabaricum, and its common names included 'Simool Tree;or 'Malabar Silk-cotton Tree of India' and that the calyx of the flower-bud is eaten as a vegetable in India."
The dry cores of the Bombax ceiba flower (Thai: งิ้ว) are an essential ingredient of the nam ngiao spicy noodle soup of the cuisine of Shan State and Northern Thailand, as well as the kaeng khae curry.
Role in Cantonese culture
Bombax ceiba is literally known as “cotton-tree flowers” (Chinese: 木棉花; Cantonese Jyutping: Muk6 min4 faa1) in China, playing a vital role in Southern Chinese, especially Cantonese, culture. It is also the official flower of Guangzhou, the capital of Guangdong Province in southern China. With some trees flowering from late February to early May. Fruiting can start as early as March. At the peak of its flowering season, elderly people could often be found picking flowers off the ground to dry, which later could be used to make a type of tea or soup. The flowers are very attractive to local wildlife, with many birds like the Japanese white-eye, a type of fruit eating bird, which often draws a hole in an unopened Bombax ceiba flower bud. Honey bees, and bumble bees also attracted to the flowers to collect pollen and nectar. Because the flowers attract many insects, crab spiders can be occasionally found on a fully opened flower, hunting bees.
- Vietnamese - (Cây) gạo rừng, gòn rừng
- Chinese - 木棉
- Cantonese (Jyutping) - Muk6 min4
- Sinhala - Katu Imbul (කටු-ඉඹුල්) 
- English - silk cotton tree, kapok tree
- Hindi - शाल्मली Shalmali, सेमल Semal
- Bahasa Indonesia - Randu alas
- Manipuri - Tera
- Assamese - শিমলু (ximolu)
- Odia- simili (ଶିମୁଳି)
- Tamil - Sittan, Sanmali, Kongam (கோங்கம்)
- Kannada - Buruga (ಬುರುಗ)
- Malayalam - Unnamurika
- Urdu - Sumbal
- Bengali - শিমুল Shimul, Shalmali
- Nepali - सिमल
- Sanskrit - Shalmali
- Sylheti - ꠢꠤꠝꠟ (himol)
- Telugu - Buruga
- Marathi - Savar, Kate Savar
- Filipino - Malabulak (Tagalog)
- "TPL, treatment of Bombax ceiba L." The Plant List; Version 1. (published on the internet). Royal Botanic Gardens, Kew and Missouri Botanical Garden. 2010. Retrieved 23 August 2013.
- Brown, Stephen H. (2011). "Red Silk-Cotton; Red Cotton Tree; Kapok" (PDF). Gardening Publications A-Z. University of Florida.
- "Shimul - Banglapedia". en.banglapedia.org. Retrieved 2017-08-13.
- J. H. Maiden (1889). The useful native plants of Australia : Including Tasmania. Turner and Henderson, Sydney.
- Thai Plant Names
- Cooking Northern Thai Food – Khanom Jeen Nam Ngeow Archived 2013-03-25 at the Wayback Machine.
- LittleBigThaiKitchen (12 March 2012). "Kaeng Khae Kai (Katurai Chilli Soup with Chicken)" – via YouTube.
- "Ayurvedic Plants of Sri Lanka: Plants Details". www.instituteofayurveda.org.
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