Members of Apocynaceae are perennial plants with simple, opposite leaves. The 5 lobed corolla forms a substantial tube, with 5 alternating stamens attached to the tube. The 5 lobed calyx is often separated almost to the base, and the single-style pistil is usally free or almost free from the calyx. As the 2 segment fruit develops, it splits apart to form separte pods that open after drying.
Some species have a milky sap that can be toxic.
The fibrous stems of A. cannabinum. were used by Native Americans for making ropes and cords. Neither species has been found on Montara Mountain at this time. Glossy, dark green, ovoid. Most trails and creek at lower elevations - prefers shaded areas. Eradication is difficult, as Periwinkle flowers and seeds continuously all year long.