Be kind to Seaside Plants--they have a tough life!
by Keene Rees
The plants that grow on Waimanalo beaches are an important part of the seashore environment. In order to survive near the ocean, they have had to adapt to living with salt spray, strong winds, intense sunshine, sandy soil, high surf, and little water. Unfortunately many of Hawaii's native plants have disappeared or become rare due to the plants, diseases, and insects that people have brought here and due to human activities on the land. Fortunately some of the remaining indigenous (native) plants are commonly seen along our shores.
The beach morning glory, pohuehue, is a vine that grows in the
sand just above the reach of the waves. The leaves make a green carpet accented
with pink bell-shaped flowers that lie close to the ground getting some
protection from the wind. The flower adapts to the hot sun and blowing sand by
opening its petals only in the cool morning hours. The vine has slender stems
called runners. Roots grow at the joints or nodes of each runner. So if pieces
of the vine are broken off by the sea or wind, new roots can develop at these
nodes and take hold in the sand. The roots help to hold sand dunes together and
stop the erosion of our beaches.
The beach naupaka, naupaka-kahakai, grows wild along many
Hawaiian shores. It usually grows close to the ground, but can grow as high as
10 feet. The naupaka has green succulent (fleshy or juicy) leaves and fruit.
This moisture protects the plant from the intense heat of the sun. The
oval-shaped leaves grow in tufts or small clusters at the tips of the long
branches. These tufts protect the growing tips from harsh sea winds and salt
spray. The white berries can float, so the currents and tides help spread the
berries, which contain the seeds of the plant. The naupaka also has a root
system that helps protect it from strong wind and waves. If a branch is broken,
new roots will form near the break to anchor the plant and keep it growing.
This adaptation has made the naupaka popular with coastal gardeners as an
ornamental windbreak and for erosion control. Most people identify the naupaka
by its small white flower which looks like it has been torn in half. Actually
the five-petaled flower is complete, but its unusual appearance has made it the
subject of several Hawaiian legends (including one retold daily at the Whaler's
Cove show at Sea Life Park).
The 'Ilima grows in many parts of Hawaii from sea level up to
2,000 ft. The plant can grow to be 4 ft. tall, but when it grows along the
coast it usually spreads out close to the ground, protecting it from the salty
sea wind. The heart-shaped leaves have many tiny hairs which help break up the
strength of the wind and keep the salt spray from the surface of the leaf. The
silvery color reflects the hot sun and helps the plant stay cool and moist. The
delicate orange-yellow blossom is the flower of Oahu. A lei `ilima has always
been highly prized and could only be worn by the ali'i in ancient times. It
takes about 1000 flowers to make a neck lei. `Ilima was equally valued for its
many medicinal uses.
Although these three plants have adapted well to the seashore environment, they are less successful in dealing with problems caused by humans. Foot traffic, dirt bikes, and dune buggies can seriously damage coastal plants by ripping and tearing the leaves, nodes, and root systems. Because the plants are important in stopping erosion of our beaches, we should take care to protect them.
Source: Kilauea Point Natural History Association, Hawaii Nature Focus No. 6