Reproductive biology of Boswellia serrata, the source of salai guggul, an important gum-resin

Abstract

Detailed studies were carried out on the phenology, floral biology, pollination ecology and breeding system of Boswellia serrata Roxb. (Burseraceae) the source of 'salai guggul'. The trees remain leafless during the entire period of flowering and fruiting. The inflorescence is a terminal raceme and produces up to 90 bisexual, actinomorphic flowers. On average a flower produces 10 044 ± 1259 starch-filled pollen grains. About 85% of the fresh pollen grains are viable; the pollen to ovule ratio is 3348 : 1. The stigma is of the wet papillate type. The style is hollow with three flattened stylar canals filled with a secretion product. The stylar canals are bordered by a layer of glandular canal cells. The inner tangential wall of the canal cells shows cellulose thickenings. The ovary is trilocular and bears three ovules, one in each locule. Flowers offer nectar and pollen as rewards to floral visitors. The giant Asian honey bee ( Apis dorsata ) and A. cerana var. indica (Indian honey bee) are the effective pollinators. The species is selfincompatible and the selfed pollen tubes are inhibited soon after their entry into the stigma. Self-pollen tubes develop a characteristic 'isthmus' as a result of enlargement of the tube soon after emergence through the narrow germ pore. Cross-pollinated flowers allowed normal pollen germination and pollen tube growth, and resulted in fruitand seed-set. Under open pollination fruit-set was only about 10%. Although manual cross-pollinations increased fruit set, it was only up to about 20%. Low fruit set appears to be the result of inadequate cross-pollination and other constraints, presumably limitation of available nutrients.

Reproductive biology of Protium spruceanum (Burseraceae), a dominant dioecious tree in vegetation corridors in Southeastern Brazil

“…Information on their reproductive biology however is available for only a few species of this family (Gupta et al 1996, Farwig et al 2004, Sunnichan et al 2005, Voigt et al 2005. Protium Burm.…”

“…Many members of the Burseraceae family, which are well-known sources of gums and resins (Sunnichan et al 2005), are dioecious and produce small flowers. Information on their reproductive biology however is available for only a few species of this family (Gupta et al 1996, Farwig et al 2004, Sunnichan et al 2005, Voigt et al 2005.…”

Male Meiotic Studies in Some Accessions of <i>Boswellia serrata</i> (Roxb.) Ex. from the Aravali Region of Rajasthan, India

“…Despite having such widespread allocation, only one species, viz. B. serrata, is found in India as a representative of the genus (Sunnichan et al 2005). In India, it is distributed in the Western Himalayas, Rajasthan, Gujarat, Maharastra, Madhya Pradesh, Bihar, Orrisa, Karnataka and Andhra Pradesh.…”

“…This is only non-coniferous source of terpentine and rosin in India. Salai guggal is commercially useful in the production of ointments, creams and capsules available in the market (Sunnichan et al 2005). The essential oils, gum and terpenoids are constituents of the gum oleo resin.…”

“…Several researchers have described the introduction, taxonomy, economic importance, reproductive biology, and medicinal value of B. serrata (Bhandari 1990, Shetty and Singh 1987, Singh and Pandey 1998, Sunnichan et al 2005. B. serrata is the only nonconiferous source of turpentine in India, and has been included in the list of threatened plants of Rajasthan (Sharma 1983, Purohit et al 1995, owing to indiscriminate removal, poor seed germination and difficulties in vegetative propagation in natural habitats.…”