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Anulocaulis leiosolenus var. howardii
(Howard's gyp ringstem)

[taxon report][distribution map][all photos][line drawing]



Family: Nyctaginaceae

Scientific Name: Anulocaulis leiosolenus (Torrey) Standley var. howardii Spellenberg & T. Wootten

Synonyms: None

Vernacular Name: Howard's gyp ringstem

R-E-D Code: 3-1-3

Description: Robust perennial herb to 1 m tall, forming large clumps; leaves mostly in 1-3 pairs in the basal 1/4 of the plant, petioles 5-10 cm long, blades broadly ovate to more or less circular, thick, leathery-succulent, glaucous bluish-green, sparsely tuberculate with small, darkened multicellular mounds; inflorescence widely paniculate, forming the distal 3/4 of the plant, the internodes with sticky glutinous bands; flowers borne in few-flowered clusters; perianth funnelform, 5-lobed, slightly zygomorphic, deep rose-pink, about 3 cm long; stamens 3, about twice the length of the perianth, deep rose-pink; style exserted slightly beyond the anthers, deep rose-pink; fruit biturbinate, 5-7 mm long, 3-4 mm wide, with 10 irregular longitudinal ridges and with an equatorial wing 0.2-0.9 mm wide. Flowers June to October.

Similar Species: Anulocaulis leiosolenus var. gypsogenus, from along the Pecos River, differs in its highly glaucous pale blue-gray green smooth leaves, its very pale pink to white flowers, and the fruit with a wing 0.8-1.2 mm wide. Anulocaulis leiosolenus var. leiosolenus, mostly from along the Rio Grande, has green leaves that are notably tuberculate, pale pink flowers, and a wing on the fruit 0.2-0.6 mm wide.


Distribution: New Mexico, Otero County, west slope of the Guadalupe Mountains.

Habitat: Open gypsum outcrop of the Yeso Formation, with limestone cobble, at about 1,350-1,450 m (4,425-4,750 ft).

Remarks: This plant is locally abundant within its restricted habitat - a single gypsum outcrop on the lower western slope of the Guadalupe Mountains. It occurs with another local endemic, Mentzelia humilus var. guadalupensis. No other populations of this ringstem are known north of the type locality where there is apparently suitable habitat. The variety was named for Michael Howard of the Las Cruces Field Office of the Bureau of Land Management, who discovered the population.

Conservation Considerations: Ranching activities on Crow Flats, the valley to the west of the locality of this ringstem, do not affect the species because, as one rancher noted, cattle don't go onto its habitat; water sources are distant. Plants were noted to be browsed late in the season, very likely by deer whose sign was evident in the area.

Important Literature (*Illustration):

Spellenberg, R. 1993. Taxonomy of Anulocaulis (Nyctaginaceae). Sida 15:373-389.

Spellenberg, R. and T. Wootten. 1999. Vascular plants on a gypsum outcrop in southern New Mexico: A listing, a new variety and taxonomic realignments in the Anulocaulis leiosolenus complex (Nyctaginaceae), and a new variety of Mentzelia humilus (Loasaceae). Sida 18(4):987-999.

Information Compiled By: Richard Spellenberg, 1999

Agency Status:
Taxon USFWS State of NM USFS BLM Navajo Nation Natural Heritage NM Global Rank
Anulocaulis leiosolenus var. howardiiSoCSoC.Sen.S1G4T1


Photo credits in header Peniocereus greggii var. greggii © T. Todsen,
Lepidospartum burgessii © M. Howard, Argemone pleiacantha ssp. pinnatisecta © R. Sivinski
©2005 New Mexico Rare Plant Technical Council