Portulaca okinawensis Walker & Tawada var. okinawensis

Kokubugata, Goro, Nakamura, Koh, Hirayama, Yumiko & Yokota, Masatsugu, 2013, Taxonomic reexamination of Portulaca okinawensis (Portulacaceae) in the Ryukyu Archipelago of Japan based on molecular and morphological data, Phytotaxa 117 (1), pp. 11-22 : 20

Portulaca okinawensis Walker & Tawada var. okinawensis

Type:— JAPAN. The Ryukyus, the Okinawa Islands , Okinawa Island , Onna , 2 October 1949, Tawada 2221 (holotype US!; available from: http://collections.mnh.si.edu/search/botany/?ti=3) .

Description: —Herbs perennial, 3–5 cm tall. Stems not articulated, diffuse, branched basally, ca. 1 mm thick; basal stems woody, prostrate, upper stems herbaceous, upright, reddish green. Root fleshy, much-branched. Leaves spirally arranged to alternate, subsessile, without axillary hairs; leaf blade 2–3 mm thick, oblong to obovate, 5–8 mm long, base obtuse, apex obtuse or rounded. Flowers solitary, about 10–15 mm in diameter. Sepals 2, ovate-deltate, about 2 mm long. Petals 5, obovate to nallowly obovate, orangey yellow, mostly without margins overlapping. Stamens 12–15. Ovary ovoid. Stigma usually trilobed or tetralobed; capsule glossy, 2–4 mm long, 2–3 mm wide.

Distribution and habitat:—The Ryukyus, the Okinawa Islands, Okinawa, Aka, Geruma, Tonaki islands. Coastal rocky slopes, xeric, saline, and exposed to direct sunlight. Portulaca okinawensis has also been recorded from Aka, Geruma, Yakabi, Tonaki, Aguni, and Kume islands of the Okinawa Islands ( Shinjo & Shinzato 2006). We have not collected samples from these islands. We examined a herbarium specimen of P. okinawensis collected from Yakabi Island (Miyagi 8414, RYU, collected in 1978) but we could not identify it at variety level because of the difficulty in counting of the number of stamens and the discoloring of the petals and stems.

Additional specimens examined:— JAPAN. The Ryukyus, the Okinawa Islands: Okinawa Island, Onna ( OK1 ), 10 August 2010, Kokubugata 12873–12878 ( TNS) ; Okinawa Island, Onna ( OK2 ), 20 September 2007, Kokubugata 9988, 9989, 10018 ( TNS) ; Okinawa Island, Onna ( OK3 ), 1 September 2010, Kokubugata 12886–12891 ( TNS) ; Okinawa Island, Yomitan ( OK4 ), 29 August 2010, Kokubugata 12867– 12872, 12879–12885 ( TNS) ; Aka Island , 30 August 2012, Kokubugata 15161–15165 ( TNS) ; Geruma Island, 30 August , 2012, Kokubugata 15166–15170 ( TNS) ; Tonaki Island , 31 August 2012, Kokubugata 15179– 15183 ( TNS) .