Honckenya peploides subsp. robusta is a perennial, reclining, mat forming herb from rhizomes and runners rooted deeply in sand, stems 10-50 cm long, pale, succulent.
Leaves opposite, each pair at right angles to next, blades yellow-green, 1-2 cm long, thick, stalkless, (sessile), tip pointed, bases broad almost meeting across stem, making ends of non-flowering stems appear cross-shaped if viewed end-on.
Flowers whitish, small, 5-parted, unisexual, near ends of stems, male flowers with petals and sepals 0.3-0.7 cm, female flowers with petals to 0.2 cm long; blooming June-July.
Fruit dry, hollow, a capsule 0.4-0.8 cm long, 0.5-1.2 cm wide, splitting into 3 sections to release many red-brown seeds, 0.3-0.5 cm long.
Wetland status: FACU.
Frequency in NYC: Very infrequent.
Habitat: Beach dunes.
Notes: Two other varieties or subspecies are found in the northwestern US and in Alaska (USDA, NRCS. 2004).