Ritha (Sapindus mukorossi) with its large leaves, is a handsome deciduous tree found in India. This tree belongs to the main plant order Sapindaceae and family Sapindeae. The species is widely grown in upper reaches of the Indo-Gangetic plains, Shivaliks and sub-Himalayan tracts at altitudes from 200m to 1500m.  Also known as soap-nut tree, it is one of the most important trees of tropical and sub-tropical regions of Asia. It is also called doadni, doda and dodan in Indian dialects.

Ritha is a common tree in Shivalik Hills and the outer Himalayas of Uttar Pradesh, Uttaranchal, Himachal Pradesh, Haryana and Jammu & Kashmir. In this entire region, starting from Afghanistan in the west to China in the east, it is found growing naturally in suitable tracts. This tree flourishes in deep clayey loam soil and does best in areas experiencing nearly 150 to 200 cm of annual rainfall.

The trunk of Ritha is straight and cylindrical, nearly 4 to 5 m in height. The canopy comprising side branches and foliage constitutes an umbrella-like hemispherical top measuring about 5 m in diameter. The tree can reach an height of 25 m and a girth of 3 to 5 m in nearly 70 years of its existence. Ritha is thus an excellent tree for planting along boulevards.

The bark of Ritha is shinning gray and fairly smooth when the plant is young. It is dark gray when the plant approaches maturity. Ritha leaves are long stalked odd pinnate. The rachis is nearly 30 to 50 cm long and bears 5 to 10 pairs of leaflets. An individual leaflet is about 7 to 15 cm long and 2 to 5 cm wide. It is acuminate and lanceolate in shape. The size of leaflets towards the tip of the rachis is smaller.

Ritha flowers during summer. The flowers are small and greenish white, polygamous and mostly bisexual in terminal thyrses or compound cymose panicles. These are sub-sessile; numerous in number and at times occur in lose panicles at the end of branches. The fruit appears in July-August and ripens by November-December. These are solitary globose, round nuts 2 to 2.5 cm diameter, fleshy, saponaceous and yellowish brown in color. The seed is enclosed in a black, smooth and hard globose endocarp. The fruit is collected during winter months for seed and or sale in the market as soap nut.

The dried fruit of Ritha is most valuable part of the plant. Its fleshy portion contains saponin, which is a good substitute for washing soap and is as such used in preparation of quality shampoos, detergents, etc. In fact the skin of the fruit is highly valued by the rural folks as a natural produced shampoo for washing their hair. They also use these for washing woolen clothes. This is why some botanists have named the species as Sapindus detergens.

Ritha foliage can be used as cattle fodder during drought. The fruit is of considerable importance for its medicinal value as well. Ayurvedic, Unani and Tibetan systems of medicine consider it to be useful for treating a number of diseases like common cold, pimples, epilepsy, constipation, nausea, etc. It is also used as expectorant and enthelmintic in small doses. The Central Drug Research Institute, Lucknow (Uttar Pradesh), has recently developed a contraceptive cream out of Ritha fruit. It is being marketed under the trade name 'Consap'.

Ritha wood is hard and light yellow in color. It is close-grained and compact weighing about 30 kg per cubic foot. The wood is utilized for rural building construction, oil and sugar presses, agricultural implements, etc.

Ritha seed germinates easily. To ensure cent per cent germination, the seed is soaked in lukewarm water for 24 hours and then sown, either directly in already prepared 60 x 60 cm pits at 5m x 5m spacing or sown in polythene bags filled with clayey loam soil mixed with farmyard manure or similarly prepared nursery beds.