Perennial, erect herb; leaves sessile, exstipulate, simple, opposite, decussate, entire, acute, linear or narrowly lanceolate; flowers fragrant, bisexual, actinomorphic, base embraced by 2 or more imbricating broadly ovate, mucronate, bracts, 3-4 times shorter than sepals, in terminal, solitary or panicled cyme; calyx gamosepalous, tubular, 5 toothed, teeth acute, finely striated, 7-9 or 11-nerves in each tooth, imbricate; petals 5, spirally arranged in bud, smooth, long clawed, limbs with fimbriate margins, pink or white; stamens usually 10 in 2 whorls, obdiplostemonous, inserted on long, stalked disc or gynophore, anthers oblong, dorsifixed; pistil bicarpellary, syncarpous, superior; styles 2, slender; ovary 1-celled; ovules numerous in free central placentation; capsule cylindric, oblong, dehiscent; seeds discoid or orbicular.