The bellflower family builds pollen pumps and has lizards as pollinators
Harebells and lobelias look modest, but their family is inventive. Some push pollen out of a tube like a piston, presenting it to visitors. In Hawaii the family evolved palm-like trees up to 14 metres tall, and on Madeira and Mauritius certain flowers are pollinated by lizards.
Campanulaceae contains nearly 2,400 species of herbs, shrubs and rare small trees, many oozing milky sap. Familiar members include bellflowers, lobelias and the balloonflower; rampion is eaten as a vegetable, while creeping bellflower can overrun gardens. The family grows on every continent except Antarctica and thrives on remote islands. Hawaii alone has well over 100 endemic lobelioids, and South Africa, California and the northern Andes are other hotspots.
Members live in parched deserts and wet forests, in lakes and on sea cliffs, and even in the far Arctic. In the Himalaya two species reach about 4,800 metres, probably the family's altitude record. Tiny cushion plants hug the high Andes, and giant rosette lobelias stand in the alpine zones of tropical African volcanoes. Some live underwater in nutrient-poor northern lakes. Island species tend to become woody, and the Hawaiian genus Cyanea includes C. leptostegia, the family's tallest member.
Flower size varies wildly, from corollas about 1 millimetre wide in some Wahlenbergia to 15 centimetres in Ostrowskia, and blue is the commonest colour. The pollen delivery is the clever part. In the lobelia branch, the anthers fuse into a tube and shed pollen into it while still in bud; the growing style then shoves the pollen up and out to waiting pollinators before becoming receptive itself. In the bellflower branch, pollen is packed among hairs on the style, released as the hairs retract, after which the stigma unfolds.
Most pollination is done by bees and birds, including hummingbirds and Hawaiian honeycreepers. Bats service some Andean Burmeistera, and long-tubed pale flowers of Brighamia attract hawkmoths. The oldest fossil seeds, from a relative of the chimney bellflower, come from Polish deposits 17 to 16 million years old. The family stores energy as inulin, and lobelias contain the alkaloid lobeline.
Source: Campanulaceae
