Reveal, J.L. and P. Veilleux. 2014. Friegonum xammei (F anew garden hybrid. Phytoneuron 2014-3: 1-3.
Published 6 January 2014. ISSN 2153 733X

ERIOGONUM xAMMEI (POLYGONACEAE),
ANEW GARDEN HYBRID

JAMES L. REVEAL
L.H. Bailey Hortortum
Department of Plant Biology
Cormell University
Ithaca, New York 14853-4301
e-mail: jlr326@cornell.edu

PETER VEILLEUX
East Bay Wilds Native Plant Nursery
28th Avenue at Foothill Boulevard
Oakland, California 94601
e-mail: pete@eastbaywilds.com

ABSTRACT
An unusual hybrid seedling involving California’s insular endemic Eriogonum arborescens
and a shrub common to the Mojave Desert, E. fasciculatum var. polifolium, was discovered in a
California nursery, which grew rapidly to form a low, spreading shrub up to 1 m high and 3.5 m
across with large, cymose, densely flowered inflorescences bearing white, slightly pubescent flowers.
The new hybrid is named here as Eriogonum Xammei Reveal & Veilleux, hybid. nov.

Hybrid populations involving insular and oastal epecits of Eriogonum Michx.
(Polygonaceae Juss.: Eriogoneae Dumortt.) are tered along the coast of California
as a result of the unfortunately widespread use of E. gigantewn S. Watson and, to a lesser extent, E.
arborescens Greene, in roadside plantings by the California Department of Transportation (Caltrans).
As a result, hybrid populations involving St. Catherine’s-Lace, E. giganteum var. giganteum, and
coastal lati of E. icul Benth. (California buckwheat), and —. cinereum Benth.
(coastal wild buckwheat), are found where these entities are in close proximity. A garden hybrid
involving the two insular species, EZ. arborescens and E. giganteum, was known for many years
before named £. xblissianum by Herbert Mason in 1938. The latter is still widely planted mainly as a
decorative plant around homes and in parks.

The discovery of another garden hybrid, especially one that grows to a large size in a matter
of months, and is even more decorative than Eriogonum xblissianum, means that the hybrid has the
potential of being an important new introduction into the California garden flora.

Eriogonum xammei Reveal & Veilleux, hybid. nov. Type. USA. California. Alameda Co.: East
Bay Wilds Native Plant Nursery, 28th Avenue at Foothill Boulevard, Oakland, 8 Oct 2013, P.
Veilleux s.n. (holotype: BH). Figures 1-3.

The East Bay wild buckwheat, Hriogonum Xxammei, differs from its maternal parent, E.
arborescens, by its fasculate leaves and broad leaf blades 0.30.8 (-1) cm wide (not solitary and 0.1-0.4(—
0.6) cm wide) and from the paternal parent by the large, cymose inflorescence (not capitate to cymose-
umbellate or rarely cymose), the cinereous lower surface of the leaf blade (not canescent or tomentose),
and from both parents by its low, spreading habit and ability to grow to a large size so rapidly.

Plants low, spreading, fast-growing shrubs, 5-10 dm tall, 20-35 dm across, sparsely
canescent; stems spreading, without persistent leaf bases, up to 1/2 height of plant, the aerial

Reveal and Veilleux: Eriogonum xammei, a new garden hybrid 2

flowering stems slender, solid, not fistulose, 0.5—1 (2) dm long, sparsely canescent;, leaves cauline,
fasciculate, the petioles 0.1-0.2 cm long, tomentose, the blades mostly narrowly elliptic, 0.5-3.5 cm
long, 0.3-0.8 (1) cm wide, densely white cinereous (except for midvein and lateral veins) abaxially,
dark green and essentially glabrous adaxially, the margins plane; inflorescences cymose, 2—-3.5 dm
tall, 2-5.5 dm across; sparsely canescent; peduncles absent; involucres solitary but in tight, congested
clusters, turbinate to turbinate-campanulate, 3-4 mm long, 2-3.5 mm wide, sparsely canescent, the
teeth 5, erect, 0.5-1 mm long; flowers 2.5-3.5 mm long, white in anthesis, becoming rose in fruit,
white-villous on the hypanthi and along the lower third of the midrib abaxially, the tepals
monomorphic, broadly obovate, the stamens exserted, 2.5-4 mm long, the filaments pilose
proximally, the anthers pink, achenes trigonous, brown, 2.5-3 mm long, glabrous.

The hybrid is named for David G Amme, long associated with the East Bay Regional Park
District, now retired, who is known for his work on grasses, especially native grass horticulture,
grassland restoration, and roadside management, and as a distinguished author on environmental
matters.

LITERATURE CITED
Mason, H. L. 1938. Ahybrid Eriogonum. Madrofio 4: 290.

Figure 1. Hriogonum Xammei Reveal & Veilleux.

Reveal and Veilleux: Eriogonum xammei, a new garden hybrid 3

Figures 2 and 3. Hriogonum Xammei Reveal & Veilleux