Blitum bonus-henricus (syn. Chenopodium bonus-henricus), also called Good-King-Henry,<ref name=BSBI07>Template:Cite web</ref> Poor-man's Asparagus, Perennial Goosefoot, Lincolnshire Spinach, Markery,<ref>Great British Bites: Lincolnshire spinach Times Online, 13 May 2008 Template:Registration required</ref> English mercury, or mercury goosefoot,<ref>Template:Cite web</ref> is a species of goosefoot which is native to much of central and southern Europe.
It is an annual or perennial plant growing up to 400–800 mm tall. The leaves are 50–100 mm long and broad, triangular to diamond-shaped, with a pair of broad pointed lobes near the base, with a slightly waxy, succulent texture. The flowers are produced in a tall, nearly leafless spike 100–300 mm long; each flower is very small (3–5 mm diameter), green, with five sepals. The seeds are reddish-green, 2–3 mm diameter.
The species was described in 1753 by Carl Linnaeus as Chenopodium bonus-henricus in Species Plantarum.<ref name="SpPl" /> Until 2012, the species was usually included in genus Chenopodium, but molecular genetical research revealed that it does not really belong to this genus. It seems to be more closely related to the genus Spinacia, and is now placed in the genus Blitum in the tribe Anserineae.<ref name="Fuentes 2012"/><ref name="GRIN" /><ref name="NCBI" /> The scientific name Blitum bonus-henricus was first used by Ludwig Reichenbach in 1832.<ref name="Reichenbach" />
Synonyms basing on the same type specimen are: Agathophytum bonus-henricus (L.) Moq., Anserina bonus-henricus (L.) Dumort., Atriplex bonus-henricus (L.) Crantz, Chenopodium bonus-henricus L., Orthospermum bonus-henricus (L.) Schur, and Orthosporum bonus-henricus (L.) T. Nees.<ref name="Tropicos" /> Heterotypic synonyms are: Blitum perenne Bubani, Chenopodium hastatum St.-Lag., Chenopodium ruderale Kit. ex Moq., Chenopodium ruderale St.-Lag., Chenopodium sagittatum Lam., Chenopodium spinacifolium Stokes, Chenopodium triangulare Dulac, Chenopodium triangularifolia Gilib., and Orthosporum unctuosum Montandon.<ref name="ThePlantList" />
Cultivation and uses
Template:Howto It should be planted in a fertile, sunny location<ref name=":0">Template:Cite book</ref> which is free from perennial weeds. Seeds must be cold-stratified in order to germinate.<ref name=":0" /> The plants should be regularly weeded and well watered. Typically, very little is produced in the first season. Good King Henry does not respond well to transplantation.
Cropping can begin in spring. Some of the new shoots can be thinned out as they appear (usually from mid spring to early summer) and cooked like asparagus. All cutting should then cease so that shoots are allowed to develop. The succulent triangular leaves may be harvested a few at a time until the end of August and cooked like spinach.