Name and stem
POWO accepts Ferocactus townsendianus as a species. The former names F. peninsulae var. townsendianus and F. peninsulae subsp. townsendianus are its synonyms. Material identified under either combination therefore remains associated with this account. Current F. peninsulae has a separate record and name circumscription. [2-WWW]
The protologue describes a short, cylindrical stem with around sixteen, often twisted ribs. The large areoles are spaced apart. Radial spines are mostly threadlike. One of the central spines may be curved or hooked. Flowers are 5–6 cm long, and their inner tepals have a pink stripe and greenish-yellow margins. [Britton and Rose 1922, p. 127]
Southern Baja California
The natural range includes southern Baja California. The type material was collected on San José Island in the Gulf of California. In the historical description, the plant grew near the coast on dry plateaus among desert shrubs. Seeds for the modern experiment were collected in June 2012 at several sites in Baja California Sur. The methods identified the material as F. peninsulae var. townsendianus. [2-WWW] [Britton and Rose 1922] [López-Urrutia et al. 2014]
A seed after interrupted water supply
López-Urrutia and colleagues germinated seeds at 30°C with a 12-hour photoperiod, on moist filter paper. Each dish held 25 seeds. One preparation treatment comprised 72 h under germination conditions, followed by drying for four, fifteen or seventy days. A second comprised one to three shorter cycles, with 24 h of hydration and four days of drying. Seeds were rewetted after preparation ended. [López-Urrutia et al. 2014, p. 92–94]
Mean germination time fell from about eight to about four days. The effect persisted even after the longest, seventy-day interruption in hydration. The molecular comparison used one cycle of 72 h of hydration and four days of drying. RNA and proteins were isolated from seeds and two-day-old seedlings. The total RNA profile retained a similar pattern after treatment, while the distribution and intensity of some protein spots on the gel differed from the control. [López-Urrutia et al. 2014, pp. 93–96]
The authors detected 321 protein spots. For 37, they proposed possible identities based on mass and isoelectric point, the pH at which a protein has zero net charge. Candidates included storage proteins, components of the ubiquitination pathway and regulators of reserve use. Such matching allows a hypothesis about the memory mechanism to be formulated. The study did not confirm these identities by peptide sequencing. The precise procedure and limits of this inference are presented in the article on hydration memory. [López-Urrutia et al. 2014, pp. 93, 96–98]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Gorelick 2007, file p. 2] [Kaktusy i Inne 2006a, file p. 42]
Synonyms and names in the literature
Ferocactus peninsulae var. townsendianus · Ferocactus peninsulae subsp. townsendianus [2-WWW]