Herbs perennial; from stout taproot, sometimes producing new shoots from lateral roots. Stems weakly erect to ascending [or decumbent], often rooting at nodes. Inflorescences solitary flowers in axils of distal leaves, sometimes forming a spike (O. organensis). Flowers: buds erect, weakly quadrangular, with free tips terminal, erect; floral-tube straight, [55–] 100–165 (–190) mm; petals obovate to obcordate. Capsules straight, cylindrical to narrowly lanceoloid, subterete, [3–] 4–5.5 [–7] mm diam. Seeds in 2 rows per locule [or in 1 irregular row derived from 2 rows of ovules (O. maysillesii Munz)], dark reddish-brown [brown], obovoid [oblong-ellipsoid], surface thickened at distal end and sometimes above raphe, [thickened area (O. maysillesii, O. stubbei W. Dietrich, P. H. Raven and W. L. Wagner) with an empty cavity]. 2n = 14.

Distribution

New Mexico, n Mexico

Discussion

Species 4 (1 in the flora).

As delimited by W. Stubbe and P. H. Raven (1979) and W. Dietrich et al. (1985), subsect. Emersonia consists of four species of mesic or xeric habitats (Oenothera stubbei) in pine-oak forests, meadows, and canyons, or boggy sites in grasslands, from scattered areas ranging from the Organ Mountains in southern New Mexico to southeastern Chihuahua, southern Coahuila and Nuevo León, northern Zacatecas and San Luis Potosí, and southern Durango, Mexico, 1100 to 2600 m. Two species are self-incompatible and two are self-compatible.

Selected References

None.

Lower Taxa

Oenothera organensis

"dehiscent" is not a number.