We studied the petiole structure of twelve American species of Pteris: P. ciliaris, P. cretica, P. deflexa, P. denticulata, P. ensiformis, P. exigua, P. inermis, P. multifida, P. mutilata, P. quadriaurita, P. tristicula and P. vittata, using both light and scanning electron microscopy. We found that petioles are characterized externally by the presence of an adaxial groove and two dorsal-lateral ventilation areas. Internally, petioles are monostelic V-, U- or inverted-Ω-shaped axes. The vascular system is surrounded by one endodermis cell layer and 1–3 pericycle strata. We propose a classification of the vascular bundles into four types considering their shape, the shape of the xylem ends, the number of protoxylem zones and the presence of parenchyma bands in the xylem.

Aquaporins are transmembrane proteins that move water specifically and bidirectionally in response to internal cell signaling. With aquaporins, plant cells can control how, where, and when water moves across membranes. Thus, plants are in strong control of their environmental responses. Therefore, it seems likely that aquaporins would have a key role in water balance in xerophytic ferns, particularly in the gametophyte stage. To investigate the role of aquaporins in desiccation avoidance in xerophytic ferns gametophytes, Cheilanthes lanosa gametophytes were poisoned with micromolar mercury solutions, which block aquaporin channels, exposed to several osmolytes, and quantified the efflux of water from the cells was quantified. Results strongly suggest that aquaporins may very well play a role in water balance, but also pose some questions concerning the ability of the protonemal stage to fully manage water flow.

The goal of this study was to determine the function of cytokinin in the morphological development and gender expression of gametophytes of Osmunda regalis, a member of Osmundales, sister-group to all other extant leptoporangiate fern families. Gametophytes of Osmunda regalis were grown in multispore populations on C-fern nutrient enriched agar containing 0, 1 nM, 1 µM, and 1 mM kinetin. Higher concentrations of exogenous kinetin reduced gametophyte size (area), disrupted correlations observed in the control between rates of apical notch formation and thallus widening, increased the proportions of asexuals and males, decreased the proportion of females in the population, and correspondingly increased male reproductive effort (antheridia per unit thallus area) and decreased female reproductive effort (archegonia per unit thallus area) compared to the control. Low concentrations of exogenous kinetin increased the proportion of females compared to the control. In the control, thalli with a comparatively deep apical notch tended to be wider (relative to their length) and possess a more circular silhouette relative to thalli with a comparatively shallow apical notch; however, these morphological parameters were independent of gametophyte size and gender. Thus, variance in the rate and planes of cell division and patterns of cell expansion and differentiation, most likely genetic in basis, were observed in the control, and the observed effects of exogenous kinetin were more than a simple “push” towards a phenotype already present in the control.

A simple and efficient protocol for isolating genomic DNA from leaves of Selaginella spp. (S. delicatula, S. repanda, S. bryopteris, S. plana, S. monospora) was developed, involving a modified CTAB protocol of Rogers and Benedich (1994). Increasing the incubation time with the precipitation buffer (1X CTAB) from 1–3 hours to 12–14 hours helped achieve higher quantity genomic DNA from the specimens, when compared with DNA extracted by protocols reported by Dellaporta et al. (1983), Murray and Thompson (1980) and Doyle and Doyle (1987). The DNA yield ranged from 846–1836 µg/ml from fresh and herbaria-preserved leaf samples. The DNA samples were found suitable for genetic diversity analysis with Random Amplified Polymorphic DNA (RAPD) markers. Nine random primers (OPA A17, OPB 4, OPB13, OPC 2, OPC 11, OPD 5, OPG 2, OPG 19 and OPK 10) were studied, of which two primers (OPD 5 and OPG 2) yielded reproducible amplification profile of polymorphic fragments.

The southern Chinese Osmunda ×mildei has been suggested to be an intersubgeneric hybrid, i.e., O. japonica (subgenus Osmunda) × O. angustifolia (subgenus Plenasium) or O. japonica × O. vachellii (subgenus Plenasium). These interpretations were based on morphological, cytological, and/or chloroplast DNA data, yet the parents of the hybrid remained unclear. Molecular phylogenetic relationships inferred here from chloroplast rbcL sequences and three nuclear DNA markers show that O. ×mildei is most likely a hybrid between the paternal O. japonica and the maternal O. vachellii.

The tree fern Highland Lace had an unusual introduction into cultivation almost thirty years ago in Eastern Australia and was initially identified as Sphaeropteris tomentosissima (Copel.) R.M.Tryon. Since then, it has been introduced to Europe and the US, and it remains a popular tree fern found in both public and private collections. We re-examined this fern, comparing it to a herbarium type specimen, and conclude that it is not S. tomentosissima, but is most likely a variant form of Sphaeropteris cooperi (F.V. Mueller) R.M.Tryon. Sequence analysis of chloroplast DNA [rbcL, atpA and trnL (UAA) intron] confirmed this species identification.

Elaphoglossum montanum, a new fern species of the Atlantic Forest in southern Brazil, is described, illustrated, and compared to the most similar species. It belongs to the Elaphoglossum “Subulate scales clade” and occurs in the upper montane forest regions in the States of Rio Grande do Sul and Santa Catarina, between 600 and 1400 m.