Authority: J. Agardh
Hawaiian name: limu manauea
Characteristic feature: Solid cylindrical stiff branches that have short pointed tips.
Description: Plants to 15 cm tall, usually 6-8 cm, forming small bushes with rounded profiles, one to several short terete to slightly flattened axes 1-2 mm diam. Arising from discoid holdfast; branching of 5-6 orders, each order shorter than proceeding one but not appreciably thinner; typically, most plants with divisions of orders 3-5 mm distant from each other, upper parts of plants densely branching, subdichotomous, irregular, occasionally trichotomous, or unilateral, the apices furcated, often coming to a sharp point; many male and tetrasporangial plants showing longer internodes (1.5-3 cm) between divisions and only 3-4 orders. Cortex a single layer of pigmented cells 4-5 by 10 mm; subcortical region of 3-4 layers of cells loosely arranged with extended pit connections, providing loose tissue between cortex and large-celled medulla; bases of hair cells common. Tetrasporangia oval, ca. 31 by 40 mm, usually collected in clusters but occasionally scattered. Sterile cells surrounding them a little modified in shape and size. Spermatangial pits deep, crowding outer cortical layers. Cystocarps occurring singly or in groups of 3-5, often in rows, globose, rarely beaked, to 2 mm diam.; tubular nutritive cells abundant.
Habitat: Mid-intertidal tide pools and eroded limestone to shallow subtidal, to 4 m.
Hawaiian distribution: All main Hawaiian Islands.
Other: Endemic to Hawaii.
Mixed with other limu and eaten with fish or meat. Hawaiian preparation involves lightly salting this limu. It is illegal to collect reproductive plants of this species; look for dark bumps on the thallus. While common, overharvesting threatens populations of this limu.
Gracilaria salicornia, a non-native invasive species successful in calm, protected waters, has brittle branches of a larger diameter, often yellow in color, forming mats on reef flats. It spreads largely by fragmentation. G. salicornia can be substituted for G. coronopifolia for consumption.