Mentha is a genus of plants in the family Lamiaceae. The exact distinction between species is unclear; it is estimated that 13 to 24 species exist. Hybridization occurs naturally where some species range overlap. Many hybrids and cultivars are known.
Mentha pulegium, commonly (European) pennyroyal, or pennyrile, also called squaw mint, mosquito plant and pudding grass, is a species of flowering plant in the mint family, Lamiaceae, native to Europe, North Africa, and the Middle East. Crushed pennyroyal leaves emit a very strong fragrance similar to spearmint. Pennyroyal is a traditional folk remedy, emmenagogue, abortifacient, and culinary herb, but is toxic to the liver and has caused some deaths. European pennyroyal is related to an American species, Hedeoma pulegioides. Though they differ in genera, they share similar chemical properties.
Pinus rigida, the pitch pine, is a small-to-medium-sized pine. It is native to eastern North America, from central Maine south to Georgia and as far west as Kentucky, and in two pockets along the St. Lawrence River in southern Quebec and Ontario. It is found in environments which other species would find unsuitable for growth such as acidic, sandy, and low nutrient soils. This species occasionally hybridizes with other pine species such as loblolly pine, shortleaf pine, and pond pine ; the last is treated as a subspecies of pitch pine by some botanists.
Justicia is a genus of flowering plants in the family Acanthaceae. It is the largest genus within the family, encompassing around 700 species with hundreds more as yet unresolved. They are native to tropical to warm temperate regions of the Americas, India and Africa. The genus serves as host to many butterfly species, such as Anartia fatima. Common names include water-willow and shrimp plant, the latter from the inflorescences, which resemble a shrimp in some species. The generic name honours Scottish horticulturist James Justice (1698–1763). They are closely related to Pachystachys.
Hydrocotyle, sometimes called water pennywort, Indian pennywort, dollar weed, marsh penny, thick-leaved pennywort and even white rot is a genus of prostrate, perennial aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae.
Hedeoma pulegioides, the American pennyroyal or American false pennyroyal, is a species of Hedeoma native to eastern North America, from Nova Scotia and southern Ontario west to Minnesota and South Dakota, and south to northern Georgia and Arkansas.
Hedeoma is a genus of flowering plants in the mint family, Lamiaceae. It is native to North and South America. They are commonly known as false pennyroyals.
Juniperus rigida, the temple juniper, is a species of juniper, native to northern China, Mongolia, Korea, Japan, and the far southeast of Russia, occurring at altitudes of 10-2,200 m. The species is also naturalized in the United States. It is closely related to Juniperus communis and Juniperus conferta, the latter sometimes treated as a variety or subspecies of J. rigida.
Mentha cervina, also known as Hart's pennyroyal, a member of the mint genus, is a sprawling herb growing up to 30 cm tall. It is native to the western Mediterranean from France south to the Azores and Algeria.
Acampe rigida is a species of orchid native to the forests of tropical southern Asia where it grows on trees and rocks at altitudes of up to 1,800 m (6,000 ft).
Euphorbia rigida, the gopher spurge or upright myrtle spurge, is a species of flowering plant in the spurge family Euphorbiaceae, native to southern Europe and southwest Asia. Growing to 50 cm (20 in) tall and broad, it is a bushy evergreen perennial with somewhat fleshy leaves arranged in a spiral, bearing bunches of bright yellow flowers in late Spring.
Persoonia rigida, commonly known as the rigid-, hairy- or stiff geebung, is a species of flowering plant in the family Proteaceae and is endemic to south-eastern Australia. It is an erect to low-lying shrub with hairy young branchlets, lance-shaped to spatula-shaped leaves that are hairy when young, and yellow flowers borne in groups of up to twenty on a rachis up to 90 mm (3.5 in) long that continues to grow after flowering.
Artemisia rigida is a species of flowering plant in the aster family known by the common names scabland sagebrush and stiff sagebrush. It is native to the northwestern United States, in Washington, Idaho, and Oregon. It has been recorded in western Montana but these sightings may have been misidentifications.
Verbena rigida, known as slender vervain or tuberous vervain, is a flowering herbaceous perennial plant in the family Verbenaceae. It is native to Brazil and Argentina, and is not fully hardy in temperate climates, where consequently it is grown from seed as an annual.
Sagittaria rigida, the sessilefruit arrowhead or Canadian arrowhead, is an aquatic plant species native to Canada and to the United States and also naturalized in Great Britain. It grows in shallow waters along the edges of ponds and streams. It generally has linear to narrowly elliptical leaves and sessile female flowers.
Ottleya rigida, synonyms Lotus rigidus and Acmispon rigidus, is a flowering plant in the pea family (Fabaceae), native to the southwestern United States and northwestern Mexico. It is known as shrubby deervetch or desert rock-pea. It is found in the Mojave Desert and Sonoran Desert.
Stachydeoma, common name mock pennyroyal, is a genus of flowering plant in the family Lamiaceae, first described as a genus in 1903. It contains only one known species, Stachydeoma graveolens, endemic to the State of Florida in the United States. It has been found only in the northwestern part of the state, referred to colloquially as the "Panhandle."
Solidago rigida, known by the common names stiff goldenrod and stiff-leaved goldenrod, is a North American plant species in the aster family (Asteraceae). It has a widespread distribution in Canada and the United States, where it is found primarily east of the Rocky Mountains. It is typically found in open, dry areas associated with calcareous or sandy soil. Habitats include prairies, savannas, and glades.
Petrophile rigida is a species of flowering plant in the family Proteaceae and is endemic to southwestern Western Australia. It is a shrub with rigid, branched, needle-shaped, sharply-pointed leaves, and more or less spherical heads of hairy yellow flowers.
Sebastiania rigida is a species of flowering plant in the family Euphorbiaceae. It was originally described as Gymnanthes rigidaMüll.Arg. in 1863. It is native to Minas Gerais and Rio de Janeiro, Brazil.
