Uniquely identifiable characteristics : A greeny yellowish very fleshy umbellifer growing on rock faces and cliffs by the seaside. It is one of several atypical Umbellifers.
Not to be confused with : Golden Samphire (Inula crithmoides) a member of the Dandelion & Daisy Family (Asteraceae)
Distinguishing Feature : Smells like shoe or furniture polish when crushed, although some report a citrus type odour. The extracted juice was formerly used to pickle foods.
In times past it was once used for pickling, and like glasswort, the spicy and salty succulent stems can be eaten raw as a snack. Or they can be boiled and eaten with butter like asparagus. The seed pods are used to flavour sauces, or can be pickled as can the green shoots. Your Author tried biting on a leaf and apart from the unusual taste, it also tasted sweetish (as well as salty), although potentially with Apiol(e) within it, he didn't want to try much.
No relation to : Marsh Samphire or Long Spiked Glasswort [a plant with similar name] which is a Glasswort (Long-Spiked Glasswort) belonging to the Goosefoot Family.
Rock Samphire is the only member of the Crithmum Genus. It is a facultative Halophyte, tolerating salt, sequestering it safely away, but not requiring it for maximal growth. Indeed, maximal growth occurs with zero salinity. Soil salinity restricts the growth of Rock Samphire, the higher the soil salinity concentration above 100mM, the more restrictive it is. Perhaps it is no coincidence that it never grows in the sea, and is always found either above the drift-line where rainwater will dilute that sea salt, or on rocky ledges and cliffs that just get sea-sprayed occasionally in storms. However, this leaves a puzzle; if Rock Samphire grows best without salt in the soil/water then why does it preferentially grow near the sea? There has to be a good reason. Perhaps it is because it is sunnier near the sea? Your Author muses: Although increasing salinity stunts its growth, it must also offer some benefit otherwise why would Rock Samphire preferentially grow near the sea; maybe it offers protection from parasites, fungi, predators or infections, or perhaps it increases the fecundity of the seeds of Rock Samphire? Aha! Eureka! Your Author was right, he has found a research paper where it says that the smallest seeds showed the highest germination percentage under salinity, but which is also modulated by the colour of the light (higher under red light than white light). Sea-sides may get a lot of red sunsets (especially those on the west coast).
The coastal shingle plants Sea Kale (Crambe maritima) Yellow Horned-Poppy (Glaucium flavum) and
Rock Samphire (Crithmum maritimum) are thermophilous, growing well and increasing in numbers with warmer summers.
Rock Samphire contains the poisonous phenylpropanoid Apiol (aka Apiole) which is related to Eugenol. It is also found in Garden Parsley (Petroselinum crispum), the arbortifacient properties of which are partly due to Apiol, which is cytotoxic in higher doses. It has been used medicinally for menstrual problems, and in the Middle Ages to aid abortion. In higher doses it can cause liver and kidney damage. Apiol is not used in medicine now.
Rock Samphire also contains the isomer of Apiol, Dillapiole, which is found in
Dill (Anethum graveolens).
ESSENTIAL OIL COMPOSITION
The essential oil distilled from Rock Samphire contains several components of which Sabinene, γ-Terpinene and
MethylThymol constitute 80%. Other reported components include para-Cymene, β-Phellandrene, (Z)-β-Ocimene, Limonene and Thymol Methyl Ether all at significant (>1%) concentrations. The sesquiterpenoid
Spathulenol (which has cyclopentane and cyclopropane rings fused to a 7-membered ring) was found in one specimen at 8.4%, but was minimal (0.1%) in other specimens.
Different populations/samples will vary in their concentration of these volatile oils, in some specimens certain compounds were absent altogether.
β-Phellandrene, a monoterpene, is also found in Fennel (Foeniculum vulgare) and in the non-native
Balsam Fir Tree (Abies balsamea) and is isomeric with α-Phellandrene but with one of the double bonds is exocyclic (outside the carbon ring). It is used in fragrances, possessing a slightly-citrusy pepperminty aroma,
Two more monoterpenes are Methyl Thymol and Thymol Methyl Ether, the latter is found in
Thyme and is also used in scents.