Polygala nana Seeds | Dwarf Milkwort
LATIN NAME: Polygala nana
COMMON NAME: Dwarf Milkwort
Plant Profile
Polygala nana is a plant you find by kneeling. It grows from a small tuber to about fifteen centimetres, with a rosette of narrow leaves and a head of violet-purple flowers that look like a clover from a distance and like a small orchid up close. The flowers have a fringed crest, and the lower petal is folded into a keel, which is the family’s signature.
The species is native to the pine flatwoods and sandy bogs of the south-eastern United States, from North Carolina to Florida and west to Texas. It flowers from spring into autumn and is one of the few milkworts that will grow in a lawn, where it survives on poor, acid sand that the grass dislikes. It is also called candyroot, for reasons that become obvious if a root is broken.
Science & Biotechnology
The root smells of wintergreen, and the compound responsible is methyl salicylate, the same oil that gives wintergreen and sweet birch their scent. In the plant it is stored as a glucoside and released when the tissue is damaged, which is presumably a defence against soil animals. The concentration is high enough that the dried root was chewed as a flavouring, and high enough that eating a lot of it is not a good idea.
The flower is built for a specific pollinator. The keel encloses the stamens, and a bee of the right size lands on the fringed crest and pushes the reproductive column out of the keel, which deposits pollen on its body. Smaller insects cannot trip the mechanism, so the plant is dependent on a narrow group of bees, mostly small andrenids and halictids.
Uses & Benefits
The root was chewed by children in the American South as a flavouring, and it was used in local medicine as a stimulant and as a treatment for coughs. The genus is a well-known one in Chinese pharmacy, where Polygala tenuifolia root is used as a sedative, but the American species is not a substitute and should not be treated as one.
The plant has no commercial crop. It is sold in native-plant nurseries as a ground cover for dry, acid sand, and it is valued in restoration seed mixes for pine flatwoods, where it establishes without irrigation. The seed is expensive and the plant is fussy about establishment, which keeps it out of the mainstream trade.
Growing from Seed
Seed is small and should be surface-sown on a sandy, acid mix, since it needs light to germinate. Keep the surface moist with a mist and give warmth, 22 to 25 degrees; germination is slow and uneven over several weeks. The plant resents transplanting, so sow where it is to grow.
It needs full sun, pure sand or a very sandy soil, and no fertiliser. In a garden, the place for it is a dry, acid bank or a patch of Florida scrub soil, and it will disappear if the ground is enriched or shaded. Water only to establish, and let it self-sow, which it does readily where the ground is bare.
Our Take
A tiny, precise flower for poor acid sand, and a plant that rewards a gardener willing to leave the ground alone.
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