Linden (Tilia europaea)

Catnip is a downy, aromatic perennial growing to 3 feet with heart-shaped, gray-green leaves and whorls of white flowers marked with purple spots. Native to Europe and naturalized in North America, it grows in dry wayside places and mountainous regions up to altitudes of 5,000 feet. The plant is gathered when in flower during summer and autumn. Catnip has an excitatory effect on cats.

California poppy (Eschscholzia californica) is an annual or short-lived perennial with finely divided leaves and vibrant orange, yellow, pink, or red blossoms. It is related to the opium poppy.

Lavender (Lavandula officinalis, also known as L. angustifolia) is a small, perennial shrub that can grow about 3 ft (1 m) high, characterized by its narrow, silver-green leaves and spiked violet-blue flowers. Renowned for its sweet aroma, lavender has a long history in traditional medicine for improving mood and sleep, and NCCIH says it is promoted today for calming anxiety and stress. NCCIH says studies suggest an oral lavender oil product might help anxiety, but more high-quality research is needed to reach reliable conclusions.

Passionflower (Passiflora incarnata and related species) is a climbing vine that can grow up to about 30 ft (9 m). It features ornate, complex flowers - often white, purple, or blue - and lobed leaves. Traditionally used as a sedative, passionflower is taken for anxiety and sleep problems; NCCIH says a small amount of research suggests it might help anxiety and total sleep time, but conclusions are not definite. Some species, such as P. quadrangularis, contain serotonin-like compounds.

Valerian (Valeriana officinalis) is an upright, clump-forming perennial reaching about 4 ft (1.2 m), with divided, pinnate leaves and pinkish-white clusters of small flowers. Known for its pungent (often unpleasant) smell, valerian has been used medicinally since early Greece and Rome, historically for insomnia, migraine, fatigue and stomach cramps. NCCIH says the evidence on sleep is inconsistent and there is not enough evidence to know whether valerian helps any health condition.

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.

Andrographis, commonly known as Green Chiretta or King of Bitters, is an upright annual herb reaching approximately 3 feet in height. Native to India and cultivated throughout northern regions of India and China, this bitter medicinal plant has been valued in Ayurvedic and traditional Chinese medicine for centuries. MSK notes that it has been studied mostly for colds, flu and upper respiratory infections. The plant thrives on plains and in forest undergrowth, where its spotted pale brown or purple flowers and long seed capsules distinguish it from other medicinal herbs.

Ashwagandha (Withania somnifera), sometimes called “Indian ginseng,” is a sturdy shrub growing to about 5 ft (1.5 m) with oval leaves, greenish or yellow flowers, and small, round fruits. NCCIH says some preparations may help insomnia and stress, but there isn't enough evidence to know whether it helps most other conditions.