Herbs (in ours) with opposite leaves. Inflorescence spike-like, terminal on stems and branches. Bracts subtending either a single bisexual flower and modified sterile flowers (micrantha) or more than one bisexual flower and triads of bisexual and sterile flowers; sterile flowers consisting of numerous hooked spines. Perianth segments 5. Stamens 5; pseudostaminodes 0. Fruit a capsule.