Tree ferns are often regarded as evergreen, non-seasonal, slow-growing plants of tropical forests. However, several species possess seasonal leaf phenology patterns and seasonal differences in growth rates. To investigate the environmental triggers which influence leaf phenology and to measure trunk growth rates, we studied a population of Alsophila firma at Las Cañadas, Huatusco, State of Veracruz, Mexico. We measured leaf traits monthly for 26 mo and trunk height at the beginning and end of the study. Alsophila firma showed a unique seasonal pattern of leaf phenology, shedding its leaf pinnules when they are yellow or still green during the wet season, and 50–70% of plants stay leafless for at least 1 mo, after which strongly asynchronous leaf flush occurs. This phenological pattern may be of advantage to evade higher herbivore pressure of the wet season and to benefit from higher light levels in the understory during the dry season when a proportion of canopy trees are leafless. The trunks had a mean height of 2.46 ± 0.16 m, a mean leaf number of 5.2 ± 0.27 (n  =  169), and 25% of the plants were fertile. Mean annual trunk growth was 17.1 ± 0.85 cm. Based on this trunk growth rate, the tallest tree ferns (>10 m) are at least 60 yr old.

The gametophytic phase of several species of Pteris has been well studied, but for others, due perhaps to their more restricted distribution, little is known. Agar and soil cultures of different spore samples of P. incompleta were established in order to analyze developmental features of its gametophytes. Gametophyte development followed the Ceratopteris pattern, but resulted in a slightly different morphology from that of other more common species of the genus. Sex expression was variable among gametophyte populations, and was affected by culture medium. An antheridiogen system was present and promoted both male precocity and dark germination. Antheridiogen response was variable among gametophyte populations. Positive antheridiogen response in interspecific gametophyte pairings suggests a common antheridiogen system in Pteris vittata and P. incompleta.

The effects of soil moisture (80%, 60% and 40% water holding capacity) on dry matter production and allocation, leaf morphological and physiological characteristics were examined in Adiantum reniforme var. sinensis, an endangered fern endemic to the Three Gorges region in southwest China. Drought stress decreased leaf growth and photosynthetic capacity, and hence reduced total mass, specific leaf area (SLA) and leaf area ratio (LAR). Dry matter allocation into the root fraction, however, increased with decreasing soil moisture. Leaf relative water content (RWC) decreased as soil water depletion, but the differences were insignificant. Such results might be the result of a physiological balance between the demand for water by the leaves and the water uptake from soil by the roots. The decrease in stomatal conductance (g_s) effectively controlled water loss and maintained intrinsic water use efficiency (WUE_i) under drought stress. The increase in proline content might contribute to osmotic adjustment, and hence sustained cytomembrane integrality in structure and function under drought conditions.

Spores of six Chinese species of Pteris (Pteridaceae) were sown on soil and subsequent gametophyte morphology and development were studied. Spores of all species are trilete, tetrahedral and with a distinct equatorial flange. Germination is Vittaria-type and the prothallial development is Ceratopteris-type in all of the species. Adult gametophytes are cordate and gametangia are of the common type for leptosporangiate ferns. Differences among species include spore size, germination time, formation time of the gametangia, gametophyte margin shape, number of archegonial neck cells and shapes of the antheridial dehiscence.

Alsophila spinulosa is a famous relict tree fern. Three polymorphic microsatellite makers were developed and characterized using the Fast Isolation by AFLP of Sequences Containing repeats (FIASCO) protocol. The polymorphism was quantified for a single population from Guizhou province, China. The number of alleles per locus varied from 2 to 4. The ranges of observed and expected heterozygosity were 0.000–0.750 and 0.218–0.651, respectively. These were the first microsatellites reported for the Cyatheaceae and will be useful for the ongoing population and conservation genetic studies of other remaining extant populations.