Hesperomannia oahuensis is a small, sprawling tree or shrub reaching 2–3 meters in height. The young branches and apical buds are densely tomentose, contributing to a soft, velvety texture. The leaves are arranged alternately, with ovate to elliptic-ovate shapes. The upper surfaces range from tomentose to sparsely pubescent, while the lower surfaces are densely tomentose. The leaf margins are either entire or dentate, adding to its varied texture. The flowering heads are on stout, puberulent peduncles measuring 6–8 mm long. The involucre is arranged in 5–8 series, displaying a color gradient from green at the bottom to magenta at the top during anthesis. The inner bracts are 2.3–2.5 cm long, and the middle bracts are 3–3.5 cm wide. The corollas are about 1.3 cm long. The fruit is a simple, dry achene (cypsela). It is found in mesic forests in the Wai‘anae Mountain Range on the island of O‘ahu between 350–900 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.