Cynomorium is a genus of parasitic perennial flowering plants in the family Cynomoriaceae.[2] The genus consists of only one species, Cynomorium coccineum (although one of its subspecies is sometimes treated as a separate species[3]). Its placement in the Saxifragales was resolved in 2016 with the help of nuclear, plastid, and mitochondrial sequences obtained from next-generation sequencing. Common names include the misleading Maltese fungus or Maltese mushroom; also desert thumb, red thumb, tarthuth (Bedouin) and suoyang (Chinese). A rare or local species, it grows in dry, rocky or sandy soils, often in salt marshes or other saline habitats close to the coast. It has had a wide variety of uses in European, Arabian and Chinese herbal medicine.[4][5][6]
This plant has no chlorophyll and is unable to photosynthesise. It is a geophyte, spending most of its life underground in the form of a rhizome, which is attached to the roots of its host plant; it is a holoparasite, i.e. totally dependent on its host. The low-growing inflorescence emerges (in spring, following winter rain), on a fleshy, unbranched stem (most of which is underground) with scale-like, membranous leaves. Dark-red or purplish, the inflorescence consists of a dense, erect, club-shaped mass, some 15–30 cm (5.9–11.8 in) long, of minute scarlet flowers, which may be male, female or hermaphrodite.[7] It is pollinated by flies, attracted to the plant by its sweet, slightly cabbage-like odour. Once pollinated, the spike turns black.[5] The fruit is a small, indehiscent nut.[8]
In the Mediterranean region, Cynomorium is a parasite of salt-tolerant plants in the Cistaceae (cistus family) or Amaranthaceae (amaranth family); elsewhere it parasitizes Amaranthaceae, Tamaricaceae (tamarisks) and, in China, Nitrariaceae,[9] especially Nitraria sibirica. Other authorities suggest the host plants are saltbushes (Atriplex species, Amaranthaceae).[5]
DNA studies suggest that Cynomorium is not a member of the Balanophoraceae, as previously thought, but more probably belongs to the Saxifragales, possibly near Crassulaceae (stonecrop family).[10][11] The issue is complicated by the massive horizontal gene transfer between Cynomorium and its different hosts. [12]
Long disputed, Cynomorium was placed in the Saxifragales in 2016, but its placement within that order remains uncertain.[13]
Cynomorium coccineum var. coccineum is found in Mediterranean regions, from Lanzarote in the Canary Islands and Mauritania through Tunisia and Bahrain in the south; Spain, Portugal, southern Italy, Sardinia, Sicily, Gozo, Malta and the Eastern Mediterranean.[14] Its range extends as far east as Afghanistan, Saudi Arabia and Iran.