Whipple’s Cryptantha (Cryptantha whippleae), serpentine-adapted species endemic to northern California

NEWS - Whipple’s Cryptantha (Cryptantha whippleae) is described as a new species from a meandering barren area in the Shasta-Trinity National Forest in Siskiyou County, California, with one outlier population in a meandering area possibly in Lake County, California.

Cryptantha is a genus of perennial herbs in the Boraginaceae (Amsinckiinae) and has been non-monophyletic in several molecular phylogenetic studies. It is currently recognized with 109 species and 124 minimum-ranked taxa, of which 63 are in North America and 47 are in South America, with one taxon found on both continents.

Serpentine soils, particularly in northern California, are formed from ultramafic (meta-igneous) rocks that formed millions of years ago on the seafloor. These soils are very high in heavy metals (e.g., nickel, iron, and magnesium) and low in calcium and potassium.

Serpentine soils are unsuitable for plants that have not evolved to tolerate the harsh conditions. Species that adapt to serpentines have high levels of endemism.

The new species is most similar to C. grandiflora and C. milobakeri, likely each other’s closest relatives. All three have large crown branchlets and small, smooth, lanceolate-ovate to ovate, slightly rounded, acuminate, and abaxially flattened fruits.

C. whippleae is relatively rare and joins 7 other Cryptantha species found on serpentines, either obligately or facultatively. Current molecular phylogenetic studies support largely convergent evolution of serpentine adaptations in Cryptantha.

C. whippleae is similar to C. grandiflora in having relatively wide corolla branches of 3-6 mm (vs. 4-8 mm in C. grandiflora) and in different size, shape and sculpture of small seeds of 3-8(15) cm (vs. 5-35 cm), in cymule branching, bifurcated or rarely solitary (vs. trifoliate) and having more seeds per fruit, 2-3 (vs. 2).

C. whippleae is similar to C. milobakeri in the width of the corolla, 3–6 mm wide (vs. 2–6 mm in C. milobakeri) and also in the size, shape, and form of the berries, which differ by 3–8(15) cm tall (vs. 10–50 cm), in the calyx shape with two types of trichomes (vs. one type of trichome) and in having more berries per berry, 2–3 (vs. 1(2)).

Whipple’s Cryptantha is endemic to northern California at elevations of 800–2200 meters. It grows in open, rocky, meandering substrate habitats. All but one known specimen is in Siskiyou County. The only specimen in Lake County is likely growing in serpentine substrate.

The species flowers from late May to early August. The berries usually ripen within a few weeks after flowering. Nicknamed after Jennifer J. Whipple, an avid collector and retired Yellowstone National Park botanist.

Original research

Simpson MG, York DA (2024). Cryptantha whippleae (Boraginaceae), a new serpentine-adapted species endemic to northern California, U.S.A. PhytoKeys 247: 155-172, DOI:10.3897/phytokeys.247.132060

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