Spermolepis hawaiiensis is an annual, slender, erect herb growing 50–200 cm high. The stems are caulescent, few-branched above, and essentially glabrous. The leaves are compound (ternately decompound) and alternate, with oblong to ovate blades measuring 1–4 cm long. The ultimate divisions are linear to linear-lanceolate, 3–6 mm long. Basal leaves soon wither, and the lowest divisions are long-petiolate. Cauline leaves are smaller, less divided, and sessile, with acute apices and scaberulous margins. Petioles are slender, 2–3 cm long, tapering into a narrow, carious-margined sheath. Stipules are absent. The flowers are in lax compound umbels arising opposite the upper leaves. The peduncles are 1–3 cm long, with an involucre of a single foliaceous bract or absent. Rays are 2–6, quadrangular, unequal, 5–15 mm long, spreading-ascending. Umbellets contain 2–6 flowers, with unequal pedicels 2–6 mm long, spreading-ascending to ascending. The involucel consists of 1–5 linear-lanceolate, scaberulous-margined, acute bractlets 1–6 mm long. The flowers are bisexual (perfect). The calyx (sepals) is absent. The corolla has 5 white petals, elliptic to obovate, without a narrower inflexed apex. There are 5 stamens inserted on an epigynous disk. The ovary is inferior, 2-celled, with 1 anatropous ovule per cell. Styles are 2, usually swollen at the base into a stylopodium. The styles are very short, much shorter than the sharply conical stylopodium. The fruit is ovoid, laterally compressed, and constricted at the commissure, measuring 3–4 mm long and 2–4 mm wide. The apex is attenuate, and the base is rounded. Mericarps are suborbicular in cross-section, covered with irregularly arranged tubercles, some bearing slender uncinate bristles concealing the filiform ribs. Vittae are large, 1–3 in intervals, and two on the commissure. The commissural face is sulcate, and mericarps readily separate. One seed per mericarp has a small embryo and cartilaginous endosperm. The seed is grooved beneath the vittae. It is known from various types of habitats, including ʻōhiʻa forests, ʻaʻaʻliʻi lowland dry shrublands, pastures, and cultivated fields at elevations between 56-725 meters.
Bean-shaped (Reniform): Resembling the shape of a kidney or bean.
Square or Oblong: Angular shape with all sides more or less equal or longer than wide.
Triangular: Three-sided shape, broadest below the middle.
Elliptic: Rounded at both ends. shaped like an ellipse or oval.
Ovate or Obovate: egg-shaped, broader at one end.
Linear: Extremely long and narrow, with sides usually parallel.
Round: Appears circular, with length and width roughly the same.
Cardioid (Heart-Shaped): One edge has a prominent double curve into two lobes.
Cylindrical: A cylinder with parallel sides and a circular cross-section.
Discoid: Resembling a disc or plate with two relatively flat surfaces.
Fusiform: Spindle-shaped, tapering at both ends.
Globose: Spherical.
Lenticular: Resembling a lens with two convex surfaces.
Ovoid: Egg-shaped.
Plano-convex: Having a flat ventral (planar) surface and a curved dorsal (convex) surface.
Polygonal: Having more than three flat faces meeting at angles.
Sectoroid: Resembling a segment of an orange with two relatively flat faces and one curved face.
Subglobose/ellipsoid: Inflated shape but less than spherical.
Trigonous: Having three faces that meet at a distinct angle; triangular in cross-section.
Endangered species (E) are species that are so rare they’re in danger of becoming extinct.
Threatened species (T) are species that are likely to become endangered within the foreseeable future throughout all or a significant portion of their range.
Species of Concern (SOC) are species about which there are some concerns regarding status and threats, but insufficient information is available to list the species under the Endangered Species Act (ESA).
Plant Extinction Prevention (PEP) is a state status for rare plants that focuses its efforts on species that have fewer than 50 remaining wild individuals.
Orthodox seeds (desiccation-tolerant): can be dried to an internal seed moisture of less than 12% water and stored at freezing temperatures.
Intermediate seeds (temperature-sensitive) tend to age faster than orthodox seeds and may have only a 5-year lifespan when stored at -20°C. They are recommended for storage at 5°C.
Recalcitrant seeds (desiccation-sensitive): cannot be stored in a conventional freezer as they cannot survive after drying and/or freezing at -20°C. They are recommended for cryopreservation storage.