Primulaceae

Mainly non-woody (herbaceous) plants (although some plants may evidently be woody at the base) with at least some fusion of petals, few stamens, and precursors to seeds (ovules) arranged freely and centrally within a single chamber in the ovary; includes Northern Starflower, 3 species of Primroses, Scarlet Pimpernel, Seaside Brookweed, Sea Milkwort, and 8 species and two hybrids of Yellow Loosestrifes.

Flower arrangement often highly modified, in various clusters (umbels, spikes, cymes or racemes) of few to many flowers at the top of the stem or where the leaves join the stem (axils), the lowermost or outermost flowers often opening first; sometimes reduced to a single flower. Flowers producing both pollen and seeds, symmetrical in at least 2 different directions (radial). Sepals usually 5, the lower part fused, the tips remaining as lobes, sometimes petal-like (in Sea Milkwort). Petals usually also 5 (but none in Sea Milkwort), often overlapping or twisted, fused at least at the base, often forming a slender tube, or bell-lke or cup-like structure, the petal tips remaining as lobes; the fused portion is often so short that the petals may appear to be separate. The lobes of both the sepals and petals may point upward or be spreading. Stamens usually 5 (sometimes 6 to 9), opposite the petals lobes, the stalks of the stamens fused to the petals. Seaside Brookweed also has modified sterile stamens. Carpels usually 5, fused; the ovary usually located above the point of attachment of the other flower parts (superior), but sometimes partially below (half inferior), e.g., in Seaside Brookweed; style 1; stigma 1, cap-like. The flowers of different individuals of the same species may have 2 or 3 different style lengths, the individuals with longer styles often having shorter stamens, a safeguard against a flower pollinating itself. Nectaries usually not present.

Fruit are capsules, opening by valves or by the top coming off as a lid.

Leaves simple, the margins entire to saw-oothed or sometimes lobed; alternate and spiral, opposite or whorled, or sometimes forming a basal rosette. Leaf veins arising from both sides of a midvein (pinnate). Stipules usually absent. Hairs, if present, often long and with cross partitions.

Plants often contain tannins, and chemicals that produce foam when mixed vigorously with water. Some family members have cavities that contain sticky aromatic yellow or red substances. Some of the Primrose species have minute glands that secrete a white, waxy, powdery or flour-like substance (farina) that coats portions of the stem, flower stalks, leaf stalks, sepals and underside of the leaves. Found mainly in cool north-temperate regions, often in high mountain areas; few in the tropics.