Leaf Growth and Phenology of the Dimorphic Herbaceous Layer Fern Danaea Wendlandii (Marattiaceae) in a Costa Rican Rain Forest

Abstract

Leaf growth and spore release in Danaea wendlandii were monitored under temperate greenhouse conditions and in a rain forest at the La Selva Biological Station in Costa Rica. Sterile leaf (trophophyll) growth occurs in four phases, and fertile leaf (sporophyll) growth occurs in five phases. Trophophylls show an initial rapid increase in length for a 4‐week period, attain full maturity at 8 weeks, and remain on the plant for about 3 years. There appears to be a seasonal pattern of trophophyll growth, with crozier emergence rates in May and June three times higher than the mean annual rate. Sporophyll growth shows a double sigmoid pattern. For about 3 weeks after crozier emergence, there is a rapid increase in length. This phase is followed by a 10‐week period with no appreciable change in length. Rapid elongation over a 2‐week period precedes spore release; this is followed within 2 weeks by disappearance of the sporophyll. Sporophylls in the rain forest are subject to 14% mortality prior to maturation, with most mortality occurring in later stages of growth. A projected phenology based on the sporophyll growth curve shows peaks in spore release late in the wet season with a concomitant peak in sporophyll emergence early in the wet season during the 15‐month period from June 1986 through September 1987.

Phenology of 16 species of ferns in a subtropical forest of northeastern Taiwan

“…Leaf life span Wagner and Wagner (1977) predicted, and some previous studies (e.g., Mehltreter and Palacios-Rios 2003;Sharpe 1997;Sharpe and Jernstedt 1990;Lee et al 2008) documented that, in dimorphic species, fertile leaves (or pinnae) are shorter-lived than sterile leaves. Similarly, the two Plagiogyria species in this study had dimorphic leaves, and the fertile leaves were significantly shorterlived than sterile leaves.…”

“…Previous studies have demonstrated that events in the fern life cycle, including leaf emergence and development, and spore maturation, occur seasonally and are influenced by rainfall or temperature (Arens 2001;Ash 1986;Farrar 1976;Farrar and Gooch 1975;Mehltreter and Palacios-Rios 2003;Page 1997;Sharpe 1997;Sharpe and Jernstedt 1990;Tanner 1983). However, these studies were conducted either in temperate regions with significant, seasonal changes in temperature, or in tropical regions with distinct dry and wet seasons.…”

“…This seasonal to non-seasonal fertility (presence of spore-bearing fertile leaves, Mehltreter and Garcia-Franco 2008) also exists on Barro Colorado Island (Croat 1978). A few other examples of seasonal (Mehltreter and Palacios-Rios 2003;Mehltreter and Garcia-Franco 2008;Sharpe and Jernstedt 1990) and non-seasonal (Tryon 1960) fertilities have been documented. In a subtropical forest where rain falls throughout the year and there is no distinct dry season, leaf emergence was not correlated with seasonal changes in precipitation (Chiou et al 2001).…”

“…In some species of ferns, fertile, spore-bearing leaves have been found to be shorter-lived than sterile leaves (see, e.g., Mehltreter and Palacios-Rios 2003;Sharpe 1997;Sharpe and Jernstedt 1990;Lee et al 2008). In these species, fertile and sterile leaves are dimorphic, i.e., they have very different morphologies.…”

“…Plant phenology is the study of seasonal changes in plant growth, photosynthesis, and reproduction (Sharpe and Jernstedt 1990). It is affected by intrinsic factors or triggered by environmental factors (Mehltreter 2008).…”