American Sea Rocket (Cakile edentula) is found in open areas along coastlines close to the sea. A member of the Brassicaceae Family, its range includes all of Cascadia. WWU SAM Project’s, with 22 observations, extinction slope is 0.64 with a projected year of extinction (without human assistance) in Cascadia Floristic Region of 2104.  Sea Rocket is related to the ubiquitous Field Mustard, a Eurasian native now naturalized throughout the Americas, also used by the Island Marble Butterfly for food, our local butterfly that recently claimed a Federal Registry slot as an endangered species.  You see Yellow Mustard growing in the Skagit Valley as a cool season crop, a type of green manure.   It may be food for certain insects, but it is doubtful that it provides a host on which Island Marbles lay their eggs, hatching caterpillars that will use the plants’ chemicals. That is, we see Yellow Mustard throughout the Northwest, but not the Island Marble Butterfly; they perhaps prefer the Sea Rocket … and the San Juan Islands must hold another host or a combination of hosts including the Sea Rocket that are becoming as scarce as the Island Marble.  There is so much we don’t know.  What we do know is that our native plant species are disappearing, as are the native animals that depend on them.

https://www.plc215.org/grasses/
https://en.wikipedia.org/wiki/Cakile_edentula
https://plants.usda.gov/core/profile?symbol=CAED
http://naeb.brit.org/uses/search/?string=Brassicaceae 
https://ecos.fws.gov/docs/recovery_plan/Draft_Island_Marble_Butterfly_Recovery_Plan_20220606.pdf

The vanishing native butterfly, the Island Marble Butterfly uses certain plant species on which they lay their eggs (for larval hosting/food) and rely on other specific plant species for their daily nutrition.  Their use of the Sea Rocket is

unknown
minimal
great

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