Its pollen is a significant cause of asthma and other allergies in warmer countries, but it is also valued as a contributor to biodiversity in polluted cities and it has been used as a medicinal herb.

[5][6] The fruits are blackish achenes and often fall with the perianth, which has a proportion of minutely hooked hairs that produce the "stickiness" for which the plant is well-known.

[4] The scientific name for spreading pellitory was coined by Linnaeus in the second edition of Species Plantarum in 1763, based on his description of a specimen collected in Palestine by Fredrik Hasselqvist (hence the specific epithet judaica (Latin): of Judaea, Jewish.

[14] The IUCN has not yet evaluated the global status of spreading pellitory, but in France, Britain and elsewhere it is considered unthreatened ("Least Concern", or LC), although in some regions it is rarer; for example, in Lorraine it is classified as endangered (EN) and it is absent from Alsace altogether.

It grows on bare soil or in the gap at the edge of the pavement and it is tolerant of light salinity, so it can occur in coastal towns and beside roads that are treated with salt.

[23] In sheltered places, spreading pellitory is an evergreen plant which typically produces smaller leaves to survive the winter (in the north) or the summer months (in warmer countries), or it dies back to a dense tangle of woody stems in less hospitable spots.

[24] The British National Vegetation Classification gives Parietaria diffusa (i.e. P. judaica) its own phytosociological community, OV41, which occurs on walls or coastal cliffs.

The OV41a wall community is rather species-poor, with typically only about 7 other plants present in a sample, most commonly the mosses Homalothecium sericeum and Tortula muralis.

[30] The larvae of the red admiral butterfly (Vanessa atalanta) and the Bloxworth snout moth (Hypena obsitalis) feed on pellitories, including spreading pelltiory,[31] as do several species of aphid, most notably Aphis parietariae.

[32][33] The pollen of spreading pellitory is one of the leading causes of respiratory allergies (asthma and rhinitis) in the Mediterranean region, particularly at peak flowering times in the spring and autumn.

[34] One study estimated that the huge population of pellitory in a city in Greece could produce as many as 5.4 × 109 (5 billion) pollen grains per square metre during the spring months, causing many medical problems.

[22] The celebrated herbalist of the early 20th century Maud Grieve considered that its "action upon the urinary calculus is perhaps more marked than any other simple agent at present employed".

Fifteen hundred years later the English herbalist Nicholas Culpeper gave a similar description but with the introduction of some errors such as opposite leaves, and considered it a useful antidiuretic and general cure-all.