Cauline leaves in 6-12+ pairs; blade curved downward, especially proximal ones, 1.2-2 mm wide. Inflorescences: branches erect to ascending. Flowers: sepals 4.5-7 mm, to 7 mm in fruit, ± glabrous or sparsely to rarely densely stipitate-glandular; nectaries narrowly longitudinally rectangular, truncate, 0.7-0.8 mm, densely minutely pubescent with erect to spreading hairs. Flowering late spring-early summer. Dry slopes and foothills, dry, yellow pine and oak forests; 600-2400 m; Calif. While B. Maguire (1947, 1951) regarded var. arcuifolia as 'a strongly marked variant,' R. L. Hartman (1993) noted that it 'intergrades with var. macradenia and might be considered the same as the latter.'

The collection from 'Forest Camp' described as Arenaria macradenia var. kuschei differs from var. arcuifolia in having densely stipitate-glandular pedicels and sepals; it does not deserve taxonomic recognition. Recently, populations of plants matching var. kuschei were discovered in the Liebre Mountains, northwestern Los Angeles County (T. S. Ross and S. Boyd 1996b). Four of the seven populations were mixed, some individuals having the stipitate-glandular pubescence of var. kuschei, and others, the glabrous inflorescences of var. arcuifolia. Furthermore, there was an east-to-west trend along the summit of Liebre Mountain from populations with a low frequency of glandular individuals to populations that were strictly glandular (Boyd, pers. comm.).