Eucalyptus (Eucalyptus globulus)

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.

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.'

Garlic (Allium sativum) is a bulbous perennial in the onion family, recognized for its sharp flavor and characteristic odor. Highly valued for both culinary and medicinal purposes, crushed fresh garlic contains allicin, which has potent antibiotic, antifungal, and antiviral properties. Regular garlic intake supports immunity, respiratory health, and circulatory function.

Hyssop (Hyssopus officinalis) is a semi-evergreen shrub growing up to about 2 ft (60 cm), with narrow leaves and clusters of bright blue, two-lipped flowers. Known since ancient times as a “cure-all” for respiratory ailments, it clears congested phlegm and supports recovery from infections. Hyssop also has antiseptic qualities beneficial for cuts, abrasions, and insect bites.

Lobelia is an annual herb growing to 20 inches with lance-shaped leaves and pale blue, pink-tinged flowers. A powerful antispasmodic used for respiratory and muscle disorders, it was a traditional Native American remedy for many conditions. It was used as a 'puke weed' to induce vomiting, as a remedy for worms and venereal disease, and as an expectorant. Lobelia was also smoked as a substitute for tobacco and was reputed to share some of its magical qualities. Indigenous to North America, especially eastern parts of the United States, it grows by roadsides and in neglected areas, preferring acid soil. The aerial parts are harvested in early autumn when the seed capsules are most numerous and are carefully dried. Its use was later championed by the American herbalist Samuel Thomson (1769–1843), who made the herb the mainstay of his therapeutic system, mainly using it to induce vomiting.

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.

Mullein (Verbascum thapsus) is an upright biennial reaching up to about 6½ ft (2 m), with distinctive gray-green, oval to lance-shaped leaves that are softly hairy, and tall spikes of bright yellow flowers. Leaves and flowers both contain saponins that assist in loosening mucus, making mullein especially beneficial for respiratory conditions such as asthma, COPD, dry coughs, and congestion. Mullein root is specifically valued for lower back pain and inflammation.