Reproductive effort and sex allocation strategy in Commelina benghalensis L., a common monsoon weed

Abstract

Commelina benghalensis L. exhibits variability in both foliar and floral features; every plant bears three types of branches and four types of flowers. The branches are negatively geotropic, positively geotropic and diageotropic. The flowers are uni-or bisexual, chasmogamous and cleistogamous. This variability influences the breeding system as well as resource allocation to male and female functions. The plants allocate c. 15% of their total resources to reproduction, the major part of which (68.9%) is devoted to production of aerial branches. The proportion of reproductive effort (RE) allocated to various branch systems is correlated with the availability of resources at the time of their differentiation. The pollen/ovule (P/O) ratio, female : male biomass ratio and reproductive output vary between different flower and branch types; variation is more pronounced in the latter. These variations notwithstanding, the results are in line with Charnov's sex allocation theory. The cleistogamous flowers of aerial branches are, however, an exception, being male-rather than female-biased. The reason behind the deviation is, in all probability, their recent evolution from chasmogamous flowers.

Genetic system of two rainy season weeds: Commelina benghalensis L. and Commelina caroliniana Walter

“…All these shoots bear flowers which vary in structure and therefore in function as well. The flowers are chasmo-or cleistogamous, bi-or unisexual and, above-or underground (Kaul 1998;Kaul et al 2000Kaul et al , 2002Kaul et al 2001). Though all shoots are floriferous, leaves differentiate only on the aerial and rarely on sub-aerial shoots.…”

“…The stigma receptivity was checked following controlled pollination as described in Gopinathan and Babu (1987). Pollen production was estimated as given in Kaul et al (2002). Insect visitation to flowers was pursued from 0530 -1200 h till the flowers remain open.…”

“…In C. benghalensis spathes of subaerial and subterranean shoots carry a single hermaphrodite flower each. In contrast, each aerial spathe has three and occasionally four di-or tri-morphic flowers (Kaul 1998;Kaul et al 2000Kaul et al , 2002Kaul et al 2001).…”

“…However, these flowers are also visited by 12 species of hymenopteran bees which are attracted by the colorful petals and anthers and profuse pollen production. The male sterile and the weakly protogynous flowers (Table 1) have a greater potential for cross pollination (Kaul 1998;Kaul et al 2000Kaul et al , 2001Kaul et al , 2002 which is carried out by the bees. In C. caroliniana, anther dehiscence and stigma receptivity commence 30-40 and 45-70 min after anthesis.…”

Reproductive Strategies in Bryophytes

“…Extensive literature is available on the reproductive biology of fl owering plants (Baker 1959 ;Doyle 1970 ;Husband and Schenoske 1996 ;Jhonston and Schoen 1996 ;Kaul et al 2002 ;Goodwillie et al 2005 ;Kudo 2006 ), but during the last few decades, the fi eld of reproductive biology has emerged as one of the most important areas of research; therefore, attention has also been drawn to understand reproductive strategies adopted by nonfl owering plants. Reproductive biology of bryophytes has been intensively studied by several workers (Saxton 1931 ;Gemmell 1950 ;Longton 1969Longton , 1974Longton , 1976Longton , 1988Longton , 1994Longton and Greene 1969 ;Clarke and Greene 1970 ;Watson 1971 ;Crum 1972 ;Nakosteen and Hughes 1978 ;Smith 1978Smith , 1979During 1979 ;Anderson 1980 ;Crundwell 1981 ;Richardson 1981 ;Anderson and Snider 1982 ;Longton and Miles 1982 ;Wyatt 1982 ;Longton and Schuster 1983 ;Udar and Srivastava 1984 ;Wyatt and Anderson 1984 ;Chopra and Kumra 1988 ;Duckett and Renzaglia 1993 ;Asthana 2001 , 2008 ;Roads and Longton 2003 ).…”