Cephalium

Cephalien ( altgr. κεφαλή kephale " head") are showy inflorescence zones, which are made ​​of several cactus plants. They occur in relatively few genera and are then typical of this species. Cacti, which form Cephalien, bloom exclusively in these separated zones. The advantages of grouping of flowers in a cephalium against solitary flowers are both better protection of flowers and fruits as well as the higher visual stimulus on pollinators.

Developmentally, there are four different characteristics to distinguish.

• Pseudocephalien ( "false Cephalien " ) are areas with increased hair formation on areoles otherwise morphologically normal shoots. They occur for example in some species of the genera Cereus and Cleistocactus.
• True Cephalien are areas with strong reinforced wool and bristle formation not only of the areoles, but also of the surrounding epidermis. In the extreme case, all epidermal cells of Cephaliums are transformed into trichomes. Spaltcephalien arise laterally and are typically sunk gap or channel-shaped in the stem axis. They usually appear on one side, sometimes on multiple pages or can often also like a jacket include the entire shoot axes. The length growth of the shoots However, this does not restricted. Spaltcephalien are typical of the genera Cephalocereus, Coleocephalocereus, Espostoa, Facheiroa, Micranthocereus, Pachycereus, Pilosocereus and Stephanocereus.
• In the genus Arrojadoa the Cephalien are formed terminally at the end of each growing season, but then grow in the new growing season. Thus, they form rings that document the annual growth of the shoots.
• The genera Melocactus and Discocactus the Cephalien are formed terminally, but not mixed, and so limit the length growth of the plant body. The Cephalien are strong deducted from the plant bodies, usually much thinner than this, at Discocactus rather small and flat, with Melocactus but up to about 50 cm high.