A Preliminary Study of the Pollination Ecology of Pedicularis in the Chinese Himalaya

Abstract

The pollination ecology of fourteen species of Pedicularis (Scrophulariaceae) was studied in the subalpinealpine zone of the Sichuan Himalaya. Bumblebees (Bombus Latr.) sternotribically pollinated rostrate, nectarless species with very long corolla tubes by scraping pollen. Pollinators on short‐tubed, nectarless, rostrate species scraped or vibrated pollen, and nectariferous species were pollinated nototribically by nectar foragers or sternotribically by pollen foragers. Stigmas contacted residual pollen in the midline of the insect body. No evidence of lepidopteran pollination was found in any Pedicularis species. Pedicularis floral structure and function are considered to have coevolved with foraging selection by bumblebees, but pollination syndromes are not specific for a single bumblebee species nor are Bombus foragers restricted to a single plant species. Analysis of corbicular pollen loads of foragers on Pedicularis revealed a moderate degree of flower constancy, especially among foragers on nectarless flowers, probably contributing to speciation in the genus. Up to nine Pedicularis species flowered sympatrically and synchronously, and some species exhibited microhabitat selection. No putative hybrids were identified. Concepts of floral evoution in Pedicularis are in need of revision in light of new evidence presented here.

The pollination ecology of Pedicularis rex subsp. lipkyana and P. rex subsp. rex (Orobanchaceae) from Sichuan, southwestern China

“…Elongation of the corolla tube in long-tubed and low species P. longiflora Rudolph var. tubiformis (Klotzsch) P. C. Tsoong has been characterized to be an adaptation to attract pollinators (Macior and Tang, 1997), very low plant height in P. muscoides subsp. himalayca is thought to be an adaptation improving pollination by queen bumblebees which stand on ground with their hind legs (Tang et al, in press).…”

“…All the previous studies have shown that Pedicularis species are self-incompatible; so development of seeds is completely dependent on pollination by bumblebees, or in a few instances by honeybees, hawk moths, or hummingbirds (Macior, 1982;Macior and Tang, 1997;Tang and Xie, 2006). A few arctic species show some selfcompatibility as an adaptation to lower pollinator visitation frequency (Eriksen et al, 1993).…”

“…It is one of the plant genera that have attracted extensive pollination studies. So far these studies have shown the only effective pollinators to be bumblebees (Sprague, 1962;Macior 1968aMacior , b, 1969Macior , 1970Macior , 1973Macior , 1975Macior , 1977Macior , 1978Macior , 1982Macior , 1983Macior , 1986aMacior -c, 1988Macior , 1990Macior , 1993Macior , 1995aMacior , b, 1996KoemanKwak, 1973KoemanKwak, , 1977KoemanKwak, , 1979Williams and Batzlli, 1982;Aluri and Robart, 1991;Eriksen et al, 1993;Macior and Sood, 1991;Philipp et al, 1996;Macior and Tang, 1997;Wang, 1998;Wang andLi, 1998, 2005;Macior et al, 2001;Tang and Xie, 2006). This does not support speculations that pollinators of Pedicularis species would be as diverse as the floral morphology implies or that species with extremely elongated corolla tubes might require specific pollinators of lepidoptera or other insects with very long proboscides (Pennell, 1948;Li, 1948Li, , 1951.…”

Absence of Long‐Proboscid Pollinators for Long‐Corolla‐Tubed Himalayan Pedicularis Species: Implications for the Evolution of Corolla Length

“…Experimental reduction of the corolla tube reduces reproductive success both in Platanthera (Nilsson 1988) and in Disa (Johnson and Steiner 1997), supporting Darwin's model of pollinator-mediated selection. Therefore, it is not surprising that several earlier workers suggested that long-tubed Pedicularis species that occur only in the Himalayas should be pollinated by very long-proboscid Lepidoptera (Pennell 1943;Li 1951;Sprague 1962;Macior and Tang 1997). Recent studies of long-tubed species through field observations indicate that bumblebees are major pollinators in addition to being important pollinators of short-tubed Pedicularis species (Macior 1990;Macior and Sood 1991;Macior and Tang 1997;Wang and Li 1998;Macior et al 2001).…”

Primary floral allocation per flower in 12 Pedicularis (Orobanchaceae) species: significant effect of two distinct rewarding types for pollinators

“…For the pollination biology of the genus in China, the previous studies have shown that export and receipt of pollen of Pedicularis species are simultaneous and almost exclusively dependent upon bumblebees (Macior and Tang 1997;Macior et al 2001;Tang and Xie 2006;Huang and Fenster 2007). Pedicularis species may be divided into two groups according to rewarding type for pollinators.…”