Indigenous. Perennial. Shrubs usually grow clumped close to the ground, but can grow up to 3 m tall. Leaves simple, alternate, crowded at stem tips, blades fleshy and succulent, surfaces glossy. Flowers several, in short axillary cymes. Corolla white to pale yellow. Split along one side and 5-lobed. Fruit a fleshy white, subglobose drupe, tolerant of salt water and buoyant, thus easily dispersed, moving along with the currents and tides around the tropical portions of the Pacific Basin.

On Midway, naupaka flowers from July through November. Fruits appear by mid-August, with an abundance in September. Some fruits can be found in December.

Introduced and naturalized. Small tree up to 5 m or more in height. Leaves simple, alternate and appearing whorled at branch tips. Blade fleshy, 10-20 cm long, densely silky pubescent (covered with soft hair) on both surfaces. Flowers sessile (lacking stalk) in stiff, widely branching. Calyx deeply divided about halfway into 5 elliptical lobes. Fruits white to green, globose, 3-6 mm long, ultimately dividing into four nutlets. Native to tropical Asia, Madagascar, tropical Australia, Tuamotus, and most of the low and high islands of Micronesia and Polynesia. A modern introduction to Hawaii. Tournefortia has become naturalized and relatively common in coastal areas on Kure, and Midway Atolls, and Pearl and Hermes Reef, Lisianski and Laysan Islands, French Frigate Shoals, and all of the main Hawaiian islands, except Kaho'olawe.

It grows in littoral forest on rocky and sandy coasts, and is particularly common in sandy open habitats of atolls, often being the tree species closest to the ocean. On Midway and other Northwestern Hawaiian Islands, Tournefornia serves as nesting habitat for our shrub-nesting seabirds. On Midway, this plant flowers and seeds from May through November.

Indigenous. Trailing glabrous vine with purple stems, often rooting at the nodes, fleshy to nearly woody from a thickened taproot, up to 5 m or more long. Leaves simple alternate, blades fleshy, oblong to suborbicular, 3-10 cm long, notched at the tip, surfaces glabrous. Flowers solitary or in few-flowered cymes up to 15 cm long. Calyx or 5 unequal, ovate to elliptical sepals 8-13 mm long. Corolla funnel-form, pink to rose-purple, 3-5 cm long, shallowly 10 lobed. Fruit an ovoid to subglobose capsule 12-17 mm long, containing 4 dark, ovoid, densely hair seeds 6-10 mm long.

Pantropical in distribution, and is found on all the major high archipelagoes of Polynesia and all the low and high archipelagoes of Micronesia. It is one of the most abundant species on rocky and sandy beaches of high islands, sometimes forming almost pure stands, but is uncommon on atolls. On sandy beaches, its creeping stems extend almost down to the high tide mark.

Native to tropical and subtropical regions worldwide. In Hawaii, common on open or grassy, often disturbed areas, from mesic coastal sites to mesic and wet forest. Found on Midway Atoll and all of the main Hawaiian islands except Kaho'olawe. On Midway, this plant can be found in disturbed and wet areas. Plants are growing, and seeding from March through November.

Eragrostis paupera

Native to the Mascarene Islands, Sri Lanka, Malaysia, northern Australia, and nearly all archipelagoes of Micronesia and Polynesia, except the Marquesas and the main islands of Hawaii. It is often the most abundant grass on rocky and sandy shores of atolls and high islands throughout the region and only rarely grows very far inland. In Hawaii, commonly occurring on coastal sands above the high-water mark, on Kure, Midway and Pearl and Hermes atolls, Lisianski, Laysan and French Frigate Shoals.

This species is an effective sand binder. On Midway, it flowers from August through November.

Portulaca lutea

Indigenous. Prostrate to weakly ascending, succulent, perennial herb with a swollen tuberous root. Leaves simple, mostly alternate. Blade ovates to suborbiscular, mostly 5-30 mm long, surface glabrous. Flowers 1-3, in terminal, congested cymes on leafy or short leafless internodes. Corolla of 5 yellow obovate petals, 9-12 mm long. Stamens 18-50 and yellow. Fruit an ovoid, capsule 6-8 mm long, opening by means of a cap that splits off to release the numerous, tiny, shiny, black seeds.

Widespread in the Pacific from New Caledonia to Pitcairn Island, north to Polynesia and Micronesia. In Hawaii, this plant occurs in coastal and strand habitats, raised coralline reef, sand dunes, and in soil pockets or cracks on all of the Northwestern Hawaiian Islands except Kure Atoll and Pearl and Hermes Reef. It also can be found on the windward, and occasionally leeward coasts of Oahu, Molokai, Lanai, Maui and Hawaii. Unlike the related cosmopolitan weed, Portulaca olearacea, it is rarely found far inland and is restricted to native habitats. Another related littoral species, Portulaca molokiniensis, is endemic to Hawaii but is very rare.

On Midway, this plant is hard to find on Sand Island, but occurs in large numbers on Eastern and Spit Islands. Identification of this plant is easily confused with the introduced Portulaca olearacea which also occurs in Midway. Portulaca has been observed flowering from July through November.

The enlarged, edible root was once used to cook with coconut cream on some Pacific Islands. Now the plant serves mostly as food for pigs. Portulaca has also been reported as an ingredient in native medicines in the Socieity Islands.

Eragrostis variabilis

Indigenous. Perennial. Culms tufted, erect, usually 4-8 dm tall or taller. Blades usually flat near base, involute in upper part, up to 50 cm long, ca. 1 cm wide. Panicles (complex branched inflorescences) narrow, up to 40 cm long, somewhat open or dense and spike-like. Caryopsis (fruit) dark reddish brown, ellipsoid to ovoid, 0.8-1.2 mm long, delicately striate.

Occurring on sand dunes, grasslands, open sites in dry forest, and exposed slopes and ridges or cliffs. On Kure, Midway (Sand Island), and Pearl and Hermes atolls, Lisianski, Laysan, Nihoa, and all of the main Hawaiian islands. On Midway, plants flower and seed from late May through late November.

Boerhavia repens

Indigenous. Perennial. Relatively robust, low and slender herb with a thickened root and several prostrate stems radiating from the root crown, sparingly to many-branched. Leaves simple, opposite, blade ovate to elliptical-ovate. Flowers several, in axillary cymes, or nearly umbellate, on peduncles. Calyx petaloid, white to pink, 5-lobed. Fruit a club-shaped to ellipsoid, 5-ribbed, 1-seeded, surface sticky.

Distributed from Africa to Hawaii and is found on all of the major archipelagoes of Polynesia and Micronesia. Common on shores and moderately dry coastal areas and leeward, at least semi-dry, lower slopes. In Hawaii, common in sandy or rocky littoral habitats, but seen frequently as a weed of coastal villages and plantations elsewhere. On Kure, Midway, and Pearl and Hermes atolls, Lisianski, Laysan, French Frigate Shoals, and all of the main islands.

In Hawaii, a similar species, Boerhavia coccinea, is a common weed of littoral and coastal areas, and differs most noticeably in having ascending branches and red flowers. On Midway, flowers in April through November, fruits and seeds from August through December.

Tribulus cistoides

Indigenous. Prostrate to ascending perennial herb with densely pubescent stems. Leaves opposite, 3-10 cm long, pinnately compound with leaflets 5-10 pairs. Blades oblong to elliptic, 8-24 mm long, silvery pubescent (with soft hairs). Flowers solitary, on a long, axillary pedicel. Calyx 6-10 mm long, split to the base into 5 lanceolate lobes. Corolla of 5 obovate, yellow petals 15-20 mm long. Fruit a green spiny schizocarp of 5 sections, each of which bears two spines up to 8 mm long.

Native to the Old World. Now pantropical in distribution, and is widespread in Polynesia (Marquesas, Tuamotus, northern Cooks, Hawaii), and in Micronesia (Marianas, Marshalls, Kiribati). It usually grows on sandy shores, but is occasionally found inland in open places at up to 400 m elevation (Marquesas). On all the Northwestern Hawaiian Islands except Gardner Pinnacles and Neker. Also on all of the main Hawaiian Islands. On Midway, you can find this plant flowering from February through November. Seeds can be found from May through December.

This plant has no reported uses, and is sometimes a nuisance because of the sharp spines on the fruit. It is closely related to the puncture vine, Tribulus terrestris, a widespread noxious weed of temperate areas of the world.

Gnaphalium sandwicensium

Perennial herb. Modestly to very densely wooly, erect to prostrate stems, olive green to white or gray, 10-60 cm long. Leaves simple, alternate. Flowers in terminal, subglobose clusters of heads, each 2-3 mm long and surrounded by many membranous, overlapping bracts. Fruit an oblong, brown achene (small, single seeded, and dry) less than 1 mm long.

Endemic to Hawaii. Found on all of the main islands, except Kaho'olawe, and on Kure and Midway atolls. It grows in dry places such as coastal sand dunes near sea level, and also inland on cinder or lava at up to 3000 m elevation, making it a facultative rather than an obligate littoral species.