Lobelia (Lobelia inflata)

Bacopa, also known as Water Hyssop or Brahmi, is a creeping succulent perennial that can grow to about 20 inches. It features spatula-shaped fleshy leaves and pale blue or white flowers on slender stalks. Thriving in marshlands and along the edges of mangrove swamps in warmer temperate and tropical climates - especially southern Asia - it develops into dense mats on mudflats. This herb has been a cornerstone of Ayurvedic medicine for supporting cognitive function and treating various nervous system disorders, and it is increasingly recognized in Western herbalism for its brain-enhancing properties.

Coltsfoot is a perennial herb growing to 12 inches with flowering stems covered in purple scales, yellow-gold flowers, and heart-shaped leaves. Indigenous to Europe and northern Asia and naturalized in North America, it is commonly found along roadsides, on verges, and in open areas. The flowers are gathered in late winter, and the leaves in summer. For at least 2,500 years, coltsfoot has been taken as a cough remedy and smoked to ease breathing. The Greek physician Dioscorides in the 1st century CE recommended it for dry coughs and 'for those who are unable to breathe except standing upright.'

Corydalis is a small herbaceous perennial growing to 8 inches with narrow leaves and pink flowers. Native to Siberia, northern China, and Japan, it is commonly cultivated in eastern and northeastern parts of China. Propagated from seed in early spring or autumn, the rhizome is harvested in late spring and early summer when the aerial parts have withered. This important Chinese remedy has been used at least since the 8th century to help 'invigorate the blood' and relieve almost any painful condition, particularly menstrual cramps and chest and abdominal pain.

Eucalyptus, a traditional Aboriginal remedy, is a powerful antiseptic used all over the world for relieving coughs and colds, sore throats, and other infections. It is warming and stimulating, and for many people its scent conjures up days spent in bed during childhood with eucalyptus and other oils smothered on the chest. Eucalpytus is a common ingredient in many over-the-counter cold remedies.

Lungwort is a perennial herb growing to 1 foot with broad oval basal leaves, smaller upper leaves mottled with white spots, and clusters of pink-purple flowers. Native to Europe and the Caucasus, it flourishes in mountain pastures and damp sites. The leaves are gathered in late spring. According to the medieval Doctrine of Signatures, which held that a plant's appearance pointed to the ailment it treated, lungwort was effective for chest ailments because its leaves were said to resemble lung tissue. This folk belief, while not scientifically founded, turned out to have merit - the herb is indeed valuable for respiratory conditions.

American spikenard (Aralia racemosa) is a tall, aromatic perennial bush up to about 6½ ft (2 m), with fleshy roots, large compound leaves, and clusters of greenish-white flowers followed by red or purple berries. Known for its warming, expectorant properties, spikenard is a tonic for weak or congested lungs.

Sweet violet is a creeping perennial growing to 6 inches tall with toothed oval leaves and attractive violet-blue or white flowers with a five-petaled corolla. Native to much of Europe and Asia, it is a common wayside plant also found along roadsides and in woodlands. In classical mythology, sweet violet was associated with death, but classical physicians recognized it as an effective emetic and cough remedy. The 17th-century herbalist Nicholas Culpeper noted that violets are cooling and moistening when fresh and green.

Wintergreen (Gaultheria procumbens) is a low-lying evergreen shrub, reaching about 6 in (15 cm), with oval leathery leaves, small bell-shaped flowers, and bright red berries. Known primarily for its oil containing methyl salicylate - a natural anti-inflammatory and analgesic compound - it has long been used for topical pain relief.