The distinguishing features of a previously unknown amphibious Isoetes discovered in coastal British Columbia, Canada are described. Although occurring in an ephemeral, vernal, seaside rock pool habitat thought to be indicative of I. nuttallii, field observations and morphological investigations determined these plants to be a distinctive taxon possessing small and boldly ornamented megaspores, relatively large microspores, and a regionally unique short velum coverage of the sporangia. It is reminiscent, particularly in spore ornamentation, of the aquatic, mid-season I. maritima and is known from one site (possibly two) where no living plants are presently evident. A unique combination of uncommon morphological features, restricted geographic range, rare habitat, and early growth season distinguishes these plants as distinct from all known Isoetes taxa. Isoetes salishensis, sp. nov. is proposed as an addition to the growing list of flora and fauna endemic to or centered on the Salish Sea area of southwestern British Columbia and northwestern Washington State.

The authors discovered a previously unknown population of Isoetes at Badami in Bagalkot district of Karnataka state, India in October 2022 which is determined to be I. bilaspurensis. This represents a new record for the Deccan plateau of Southern India and a significant disjunction from its previously known distribution in Chhattisgarh and Madhya Pradesh, Central India. In light of this additional information a revised, detailed description of I. bilaspurensis is presented. Morphological comparisons with closely related taxa, its conservation status, and the phytogeographic implications of its distribution are also provided.

Cystopteris fragilis is widely distributed globally, particularly in the northern hemisphere and in temperate montane regions of the southern hemisphere. Nonetheless, there is limited published evidence of its physiological ecology. This is a report of the physiological ecology of C. fragilis growing in the crevices of a stone wall in Palisades, N. Y. during the summer of 2022 when the northeastern U. S. A. experienced an extended period of excessive heat and drought. Highest laboratory measurements of maximum rehydrated photosynthesis rate (A_c) occurred in June (1.83 µmol CO₂ m^–2 s^–1) prior to the onset of the more severe heat and drought in July and August when the photosynthesis rates declined (1.47 and 1.58, respectively). The lowest rate was found in September (1.41) prior to onset of leaf senescence and dehiscence. Dark respiration (R_d) followed a comparable trend with the highest rate in June (0.82 µmol CO₂ m^–2 s^–1), with lower rates in July, August, and September (0.40, 0.43, and 0.55, respectively). Additional evidence is presented on leaf fluorescence including chlorophyll concentration index (C.C.I.) as well as PS II data on quantum yield efficiency (F_v/F_m) and electron transfer per reaction center (ET₀/RC) during each of the five months. This study provides the first evidence that C. fragilis can be a desiccation-tolerant, ‘resurrection fern’ capable of dormancy enduring extreme dehydration and resumption of normal physiological activity within 24 to 48 hours after heavy precipitation events.

Adiantum forzzanum and A. matogrossense (Pteridaceae) are described as new from west-central Brazil. Adiantum forzzanum resembles A. lorentzii, and A. matogrossense resembles A. ruizianum and they were previously identified as such. Both species, however, can be distinguished by their yellow-farinose indusia and the presence of glands that produce farina (whitish or cream-colored, or yellowish) on the lamina abaxially. These two new species are described, illustrated, and discussed, and a key to distinguishing all other closely related species of the A. raddianum group in the Neotropics is also presented. This contribution adds two more endemic species of Adiantum to the flora of Brazil and is part of our ongoing effort to improve the circumscription of the A. raddianum group.

The population dynamics of rock fern Asplenium septentrionale in Estonia was monitored from 1994 to 2020; the data were analysed to understand how the rhythm of local weather variables affects the population condition and renewal. Both fern clump size and life stage (sporeling, premature, mature, senescent) structure of the population were studied. Our results indicate that the population has been stable, with a high proportion of reproductive adults. Precipitation distribution through all seasons of the year had a major impact on population recruitment. June was the key period of the year determining the survival of young sporelings. Higher rainfall in the previous year supported higher numbers of premature clumps in the following year. The number of mature fern clumps was most influenced by weather conditions during winter months and precipitation at the end of summer. The long-term survival of mature clumps might be threatened if periods without rainfall extend into the growing season and occur during consecutive years. Monitoring methods of nationally protected fern species should be improved by including individual-based observations on life stage transitions of young sporophytes (sporeling to premature, premature to mature) for predicting future trends in population conditions.