Seaside plantain is a perennial growing to 0.2m. . The flowers are
hermaphrodite (have both male and female organs) and are pollinated by
Wind. The plant is self-fertile.

The plant prefers light (sandy), medium (loamy) and heavy (clay) soils
and requires well-drained soil. The plant prefers acid, neutral and
basic (alkaline) soils and can grow in saline soil. It cannot grow in the
shade. It requires dry or moist soil. The plant can tolerate maritime
exposure.

It grows on the rocks at Race Rocks where the soil is well drained and
dry. It is exposed to the sea spray and so it can tolerate changes in
salinity.
It is used is a laxative - Plantain seeds contain up to 30% mucilage
which swells up in the gut, acting as a bulk laxative and soothing
irritated membranes. Sometimes the seed husks are used without the seeds.

The young leaves are edible leaves raw or cooked.

Reference:
http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=529711

http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Plantago+decipiens&CAN=LATIND