Approximately 249 plant taxa have been reported on Midway from the time it was first discovered through 1992. Of these, 119 taxa were known only from cultivation, 104 taxa had become naturalized from either intentional or accidental introductions, and 24 taxa were native to Midway.
The most common and in most cases, invasive/noxious, introduced taxa include Ironwood (Casuarina equisetifolia), Golden crown-beard (Verbesina enceloides), Wild poinsettia (Euphorbia cyanospora), Haole koa (Leucaena leucocephala), Sweet alyssum (Lobularia maritima), Buffalo grass (Stenotaphrum secundatum), Peppergrass (Lepidium virginicum), and Bermuda grass (Cynodon dactylon).
Fifteen of the native taxa are indigenous, or found elsewhere beyond the Hawaiian Islands, and nine are endemic to the Hawaiian Islands. None of the endemic taxa are restricted to Midway Atoll (Wagner et al. 1990).
Scaevola sericea
Hawaiian name: Naupaka kauhakai
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.
Occurring throughout tropical and subtropical Pacific and Indian Ocean coasts; found on all the major archipelagoes of Polynesia and Micronesia. In Hawaii, common in coastal sites throughout the Hawaiian Archipelago, except Gardner Pinnacles, Necker, and Nihoa. One of the most common littoral shrubs, often forming dense thickets on rocky and sandy coasts.
Tournefortia argentea
Common name: Tree heliotrope 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.
Since the tree is small, it is not very good for timber, but the wood is sometimes used for making gongs, canoe bailers, tool handles and carved handicrafts, and parts of the tree are reported to be used in native medicines in the Society Islands and Tokelau. The leaves were once used in the preparation of a red dye in Tahiti.
Lepturus repens
Indigenous. Perennial with branched stolons (a stem that grows horizontally, a runner). Culms tufted, erect or spreading, slender, 1-6 dm tall, branching. Spikes straight or slightly curved, 3-20 cm long. Spikelets 1-flowered 10-14 mm long, usually tipped with a rigid awn. Caryopsis pale brown, oblong to obovate, ca. 2 mm long, dorsally compressed.
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.
Wildlife Midway in Islands