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Calotropis gigantea, the crown flower, is a species of Calotropis native to Cambodia, Bangladesh, Indonesia, Malaysia, the Philippines, Thailand, Sri Lanka, India, China, Pakistan, Nepal, and tropical Africa.It is a large shrub growing to 4 m (13 ft) tall. It has clusters of waxy flowers that are either white or lavender in colour. Each flower consists of five pointed petals and a small "crown" rising from the center which holds the stamens. The aestivation found in calotropis is valvate i.e. sepals or petals in a whorl just touch one another at the margin, without overlapping. The plant has oval, light green leaves and milky stem. The latex of Calotropis gigantea contains cardiac glycosides, fatty acids, and calcium oxalate. The roots also contain Calotropone. It is the host plant for Hawaii's non-migratory monarch butterflies. Calotropis is an example of entomophily pollination (pollination by insects) and pollination is achieved with the help of bees. In Calotropis, gynostegium is present (formed by the fusion of stigma and androecium). The pollen are in a structure named pollinia which is attached to a glandular, adhesive disc at the stigmatic angle (translator mechanism). These sticky discs get attached to the legs of visiting bees that pull out pollinia when a bee moves away. When such a bee visits another flower, this flower might be pollinated by the pollinium. Habit : A large shrub, much branched, gregarious, young branches covered with white, cottony hairs, contains milky latex. Stem : Erect, branched, cylindrical, solid, contains milky latex. Leaves : 4-8 inches long, decussate, obovate or elliptic-oblong, shortly acute, subsessile, cordate or often amplexical at the base. Inflorescence : Umbellate cymes. Flowers :Large, white, not scented, peduncles arising between the petioles. Flower-buds ovoid, angled, Calyx lobes 5, divided to the base, white, ovate; corolla broadly rotate, valvate, lobes 5, deltoid ovate, reflexed, coronate-appendages broad, obtusely 2-auricled below the rounded apex which is lower than the staminal-column. Stamens 5, anthers short with membranous appendages, inflexed over the depressed apex of the pentagonal stigma. Pollinium one in each cell, pendulous caudicles slender. Carpels 2 distinct, styles 2, united to the single pentagular stigma, ovary 2-celled, ovules many. Fruit : A pair of follicles with many, hairy seeds. Flowering and Fruiting Time : November-April Common as a weed in waste lands. The root, bark and milk used in medicine for the treatment of dysentery cutaneous affections. The leaves are applied on paralysed parts, painful joints. The milk is useful in leprosy and ringworm.
Yala National Park. coastal lowlands. The Yala area is mostly composed of metamorphic rock belonging to the Precambrian era and classified into two series, Vijayan series and Highland series. Reddish brown soil and low humic grey soil are prominent among six soil types. Yala is situated in the lowest peneplain of Sri Lanka, which extends from Trincomalee to Hambantota. Topographically the area is a flat and mildly undulating plain that runs to the coast with elevation is 30 metres (98 ft) close to the coast while rising in the interior to 100–125 metres (328–410 ft). The national park is situated in the dry semi-arid climatic region and rain is received mainly during the northeast monsoon. The mean annual rainfall ranges between 500–775 millimetres (19.7–30.5 in) while the mean temperature ranges between 26.4 °C (79.5 °F) in January to 30 °C (86 °F) in April. It is windier in Yala, during the southwest monsoon compared to the wind during the northeast monsoon with wind speeds from 23 kilometres per hour (14 mph) to 15 kilometres per hour (9.3 mph). Water is abundant after the northeast monsoon, but during the dry season surface water becomes an important factor. The bodies of surface water appear in the forms of streams, tanks, waterholes, rock pools, and lagoons. Waterholes occur in low lying places while rock pools of varying size are capable of containing water year-round, and are hence an important source of water for elephants. For many water birds and water buffaloes natural waterholes are ideal habitats. Such reservoirs are largely concentrated to the Block I followed by Block II. Several tanks are there including, Maha Seelawa, Buthawa, Uraniya, and Pilinnawa tanks. Many rivers and streams flow in a southeasterly direction, originating in the highlands of adjacent Uva and central hills. Kumbukkan Oya in the east and Menik River and its tributaries in the west flow across the park, and provide an important water source in the dry season to wild animals of the park. Normally the streams of the park are dry during the drought season. These rivers and streams exhibit a degree of runoff fluctuations between wet and dry seasons. Kumbukkan Oya discharges seven times as much water in the rainy season than in the dry season. A number of lagoons are situated along the coast line of the park.