CAMPANULALES

the bellflower order of flowering plants, belonging to the class Magnoliopsida (dicotyledons; characterized by two seed leaves). Its members are mostly herbaceous and perennial and are of chiefly ornamental value. Seven families, 105 genera, and about 2,500 species are placed in Campanulales. The most familiar plants are those in the bellflower (Campanulaceae) family; Lobelia species are also well-known garden ornamentals. Members of the Campanulales grow at elevations ranging from sea level to 4,000 m (13,000 feet). The bellflower family grows in mountainous areas of temperate regions in both hemispheres; some lobelias are native to the temperate Northern Hemisphere, but a larger number are found in the milder areas of the Southern Hemisphere and in the tropics. Representatives of the other, smaller families are mainly Australian. The diversity in distribution of this order is matched by the diversity of habitats. In the genus Campanula, for instance, many species prefer sunny locations, others grow best in shady woodlands, and C. aparinoides of North America is found in marshes. The majority of bellflower species thrive on soils derived from limestone, but C. loeflingii of Portugal grows in somewhat acidic, sandy soils. Lobelia siphilitica and related species grow in open, sunlit fields saturated with water. On the other hand, species of Nemacladus are annuals in the deserts of the southwestern United States. Of the 40 genera and 700 species belonging to the Campanulaceae family, 17 genera are favoured for their beauty. The Adriatic (Campanula elatines) and the willow (C. persicifolia) bellflowers, with origins in Europe and northern Asia, have yielded several cultivars ranging in colour from white to blue. The tussock bellflower (C. carpatica) of the Carpathian Mountains forms clumps 45 cm (18 inches) tall. Species native to eastern North America but also grown in gardens are the bluebell (C. rotundifolia) and the tall bluebell (C. americana). The creeping bellflower (C. rapunculoides) is a notorious garden weed. Of more than 100 species in the genus Wahlenbergia (widely distributed from western Europe to the Southern Hemisphere), eight are under cultivation; the trailing bellflower (Cyananthus) of the Himalayas is known for its mat-forming species. Among the few food plants produced by the Campanulaceae are the rampion (Campanula rapunculus), eaten as a vegetable in parts of Europe, and some robust members of the bellflower familyespecially Canarina, Clermontia, and Centropogonthat produce edible berries. Familiar Lobelia species include the cardinal flower (L. cardinalis), which displays a brilliant red corolla in contrast with the blue or white colours of the majority of related species. Indian tobacco (L. inflata) is native to eastern and central North America; it has a tobacco taste and was used as an emetic by indigenous Indians. This and other lobelias yield an alkaloid, lobeline, useful as a remedy against nicotine addiction. Campanulales reproduces almost universally by seeds. The elongated, upper portion of the leafy stem becomes an inflorescence (flower cluster) as a flower bud arises in the axil (angle between stem and petiole) of a leaf. The inflorescence is a raceme (if flowers are stalked) or a spike (if flowers are unstalked). A generalized flower of this order possesses five green, partly united sepals, which form the calyx. Usually, the five petals form a corolla tube, which may be closed, typically bell-shaped, or widely spreading. Fewer than five stamens (male) develop in some genera. Three elongate carpels form a closed structure, the pistil (female); it comprises a swollen, basal ovary containing ovules and a slender style that ends in a three-lobed pollen-receptive stigma. Flower parts arise atop the ovary. The matured ovary (or fruit) ripens dry; it is a capsule and releases its seeds by opening longitudinally or in other ways. Seeds are numerous in the bellflower and lobelia families, but few in the remaining groups. The corolla of the bellflower family is radially symmetrical (petals alike in shape and size), but in the lobelias half the corolla is the mirror image of the other half (bilateral symmetry). In the Campanulaceae, pollen is released from the anthers while flowers are still in bud and the stigma is unreceptive; stiff hairs on the centrally placed style hold the pollen grains until the corolla opens. Insects, attracted to the nectar at the base of the style, brush against the pollen and carry it to older flowers in which the stigma has become receptive. Cross-pollination is effected in this manner. In Hawaiian species of Clermontia, the curving corolla tube matches the bill of the pollinating bird, the honey-creeper.