ʻĀkia has this reddish stem, but when it matures it changes color and has white rings around the stem. The leaves point upwards, but not always. ʻĀkia is common and the best place to see it is on the Konahuanui trail and Aiea Ridge trail. Do not eat the ʻĀkia berries as some say it is poisonous. There are however, varying species of ʻĀkia that look different than the common red stem/white rings species.
Background Information
ʻĀkia is an endemic species in the Daphne family. I'm not familiar with the Daphne family, but after some basic research, cultures from around the world make paper out of the plant. The berries are poisonous in some species of ʻĀkia. In ancient times, Hawaiians used the plant to make rope. Hawaiians also used the ʻĀkia berries to make a concoction to execute criminals, akamai these Hawaiians. In modern times, ʻĀkia is a nice plant for landscaping, especially the uva-ursi species. But watch out the berries are poisonous.
ʻĀkia
This species of ʻĀkia is called Wikstroemia oahuensis. It is the more common one on Oahu. It can grow into a shrub or a tree. The tree isn't too tall, but I've seen some that can reach up to 20 feet high. The stem has white rings around it which can be the give away. The other give away is the red bark, almost maroon like. The flower is small with 4 petals with a greenish/yellowish color. You may get this plant mixed up with manono. But with experience, you can make the distinction right away. The berries go through different colors as they get riper. They are green and turn orange as they get riper. However, don't eat the berries because it is poisonous.
Konahuanui
ʻĀkia
Here are some green berries, they are small in size. The stem has white rings around it. The tree is solid and very sturdy.
ʻĀkia
I'm not sure the name of this species of ʻĀkia. As you can tell the leaves seem softer than the other more common species (Wikstroemia oahuensis). The flower does look the same.
Poamoho
ʻĀkia
This species of ʻĀkia is called Wikstroemia uva-ursi. It occurs near the beach. It has a cluster of yellow flowers. The symmetry of the leaves is impressive. On Oahu, I've only seen it in native gardens and not on the beaches, however on Maui it occurred on the beach.
Waikiki Aquarium
First time I seen in the wild @ Waihe'e Coastal Dune in Maui
Green berries
ʻĀkia
Here is another species of ʻĀkia I saw while hiking in the Northern Waianaes. It kind of looks like the one above that I was unable to identify.
Sources
Flowering Plants of Hawaii, 1282-1291
Hawaiian Plant Life, 163-164