Bartram’s Stonecrop

Bartram’s stonecrop is typically found in deep, narrow, heavily shaded canyons with erodible soils within Madrean woodlands at elevations ranging from 1,067 to 2,073 meters. Bartram’s stonecrop plants are almost always located near water sources like springs, seeps or intermittent streams, but above the floodline. This proximity to water, coupled with shade from trees and rock walls and a deep litter layer, collectively provide increased humidity and decreased temperature in the plant’s microclimate.

The Bartram’s stonecrop is a small, perennial plant in the stonecrop family Crassulaceae. The species has a succulent basal rosette that is 7 to 16 centimeters wide and is comprised of 20 or more flat to concave, smooth, blue-green leaves with a waxy coating. During the fall, Bartram’s stonecrop produce one to seven showy flowering stalks that are up to 30.5 centimeters in height. The number of flowers per stalk and the number of stalks depends on the size and age of the plant with larger older plants having numerous stalks and up to 214 flowers. Flowers are yellow-petaled with brown-red dots that resemble writing, hence the scientific name Graptopetalum, meaning written on petals. The fruits are capsules that, in November and December, split along the side to release minute seeds that are less than 1 millimeter wide and resemble dust.

Bartram’s stonecrop flowering is triggered by fall rains and does not occur during periods of water stress. Although Bartram’s stonecrop adult and immature plant numbers fluctuate annually pending drought and other threats, seedling numbers can fluctuate even further due to the vulnerability of this life stage to desiccation.

Bartram’s stonecrop flowering stalks grow in July and August with flowers produced in September to November. Individual Bartram’s stonecrop flowers open in succession, such that the length of time each flower remains open overlaps, allowing for various stages of flowering and fruiting to be simultaneous within an individual plant for a month or more. Bartram’s stonecrop seeds may be dispersed via water, gravity and wind. It is generally thought that the Bartram’s stonecrop soil seedbank may last one to two years under field conditions, with most germination occurring the year following seed production. Bartram’s stonecrop does not reproduce vegetatively and is dependent on pollinators and seed production for reproduction. Winter precipitation is needed for Bartram’s stonecrop germination, though some germination likely occurs following summer rains, and both summer and fall precipitation is needed for flower production.

The lifespan of Bartram’s stonecrop is thought to be approximately five years. This was determined from three individuals that were first measured in 2013, still being alive and mature in 2017. We are aware of several populations that have been observed at or near their originally observed location over time, which indicates that these populations are persisting and are self-sustaining over a period of several decades.