Cyathophylls as long as involucre, membranous. The pistillate heads consist of two pistillate flowers surrounded by a spiny involucre. The whorl of bracts at the base of the flower head (involucre) is long. Usually six flowers bloom in a bell-shaped involucre of five partly fused bracts. Some species have sessile flowers, often in an involucre. Below the head is an involucre of glabrous green bracts long with brownish edges. Similarly, the 'calyx' is an involucre of bracts. In general, an involucre is a covering. A set of bracts forms an involucre surrounding the base of the capitulum. The pseudanthium has a whorl of bracts below the flowers, forming an involucre. Bracts that appear in a whorl subtending an inflorescence are collectively called an involucre. The involucre is in diameter, and consist of two strict rows of bracts of long. The involucre changes from greenish-white to dull brown as the fruit matures.