[1][2][3] While Vaccinium as a larger group is characterized by an inferior ovary and brightly-colored berries that are indehiscent,[2] the Hawaiian group has traditionally been distinguished as having uniquely well-developed calyx lobes and longer calyx tube depth, more cylindrical corolla shape (as compared to urceolate-globose), reduced or absent staminal awns (as opposed to well-developed), longer pedicel length, and — compared with temperate relatives — much longer leaf persistence.

However, confidence in the existing molecular evidence for this hypothesis is low, and therefore the status of the sister group to the Hawaiian clade is still unknown.

[3] Hawaii is known as a historical hotspot for adaptive radiation because of immense biological opportunity over small, isolated areas, especially advantageous for plants that colonized the islands when they were first formed by volcanic activity.

The key distinctive morphological feature separating Vaccinium cereum from the Hawaiian taxa is the pseudo-10-locular ovary, which is similar to ovary structure common of Asian Vaccinium species, as opposed to the strictly 5-locular present in most New World species and the Hawaiian taxa.

However, as noted above, the Hawaiian taxa are hypothesized with moderate confidence to belong in the Myrtillus section, which is primarily North American.

However, these are simply exciting postulations for now, as there is much uncertainty surrounding the evolutionary history South Pacific Vaccinium in general.

These findings support that a Japanese species is just as likely to be closest in genetic relation to the Hawaiian taxa than the North American members.

[5] Vaccinium reticulatum is a rhizomatous, evergreen shrub, characterized by stiffly erect aerial shoots, often pubescent throughout.

[1] Leaves ovate at 1-3 cm long and wide and typically exhibit pubescent and/or serrate margins, but not always.

[5] Physically, the primary character of distinguishability of this species, denoted in Vander Kloet’s keys, is stout pedicels: .5-1.5cm long.

[1] Vaccinium dentatum is typically found decumbent to sprawling, 0.3 to 3 m tall, mostly on terrestrial edges and open areas: bogs, swamps, or windy exposed ridges.

Flower variation is less than that in V. reticulatum: carolla red or pink with greenish lobes, 9-12 mm long.

Its elevational and geographical range mirrors that of Vaccinium dentatum: 500-1,800m, on all main islands, though it is not well known whether these taxa occur together.

The defining characteristic unique to Vaccinium calycinum is perhaps its deciduousness, but the degree of this character is relatively weak: plants are found without leaves for 1-3 weeks from October to February.

The designated distinguishing character is again the calyx, which in Vaccinium calycinum is foliaceous and overlapping in bud and 2–3 mm wide at base, longer than the tube at antithesis.