Caryophyllaceae - Campion Family

Bladder Campion (Silene vulgaris)

The Caryophyllaceae (Campion family) include White Campion (Silene latifolia), Red Campion
and Bladder Campion (Silene vulgaris, above). The infloresecnce is a cyme, meaning that it has sympodial branching with branches terminating in flowers. The cyme has either a single main axis (monochasial cyme) or two main axes (dichasial cyme). Note the tube of fused sepals enclosing the tube of petals.

Above: the bracteoles of campions are well-developed. These are leaf-like structures (bracts) subtending each flower stalk or pedicel. (Bracts proper subtend the flower itself). The contorted (convolute) imbricate aestivation is clearly visible in the flower bud on the right. Aestivation (prefloration) is the folding of flower parts into the bud. Imbricate means the edges (of the petals in this case) overlap and convolute or contorted means that each petal has one edge out (over the in-tucked edge of the preceding petal) the other one tucked in to the next petal.

Bladder Campion (Silene vulgaris) is immediately recognizable with its hollow, bladder-like flower tube (corolla) and surrounding tube of fused sepals (calyx tube). It is a fascinating example of a curious biological phenomenon - it is gynodioecious. Gynodioecious plants come in two different genders: female individuals (with reduced and sterile male parts) and hermaphrodite individuals. The hermaphrodites have longer anthers and longer staminal filaments and smaller ovules than the female plants. They also have longer petals and wider corollas. This raises interesting questions concerning the evolutionary advantage of gynodioecy.

In an attempt to understand the significance of this phenomenon research has examined the various trade-offs in the two forms (Dykstra et al. 2009. Int. J. Plant Sci. 170(5): 575–583). For example, in hermaphrodites the ovule size is inversely proportional to anther length, so anthers tend to be shorter when ovules are larger and vice versa, suggesting that male and female function are competing for the same resources. Internode length in hermaphrodites was also inversely proportional to ovule number, suggesting that plants growing in shade (which elongate their internodes in an attempt to reach more light) invest fewer resources on female reproduction, whilst male reproduction remains unaffected. In contrast, in females these correlations are not found, but instead ovule size is inversely proportional to ovule size, suggesting that flowers with more ovules have smaller ovules, indicating a limited resource allocation. In female plants, internode length correlates with ovule number, meaning that taller plants tend to have more ovules, so female reproductive capacity is not being compromised in plants growing in shade.

Above: the typical campion petal shape is readily apparent, consisting of a narrowed basal part or petal claw, and a two lobed or bifid apex. A protruding appendage is associated with the top of the claw, together forming a protruding rim. Some researchers consider the petals to be modified stamens in Caryophyllaceae. The stamens of this family typically fuse into a stamen tube. There are typically ten stamens, five aligned with the five sepals (antesepalous) and five aligned with the five petals (antepetalous). The fruit are dry and dehiscent, splitting open when ripe.

The ovary bears 3 to 5 styles (3 in this case). Each of the five petals is split into two lobes and there are two bosses at the base of each petals representing the scales that occur in other species.

Silene vulgaris is native to most of Eurasia and parts of north Africa but naturalized in some other regions, especially  North America. (See: https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:158668-1).

White Campion (Silene latifolia)

The flowers open fully in the evening when they become slightly fragrant. Each of the five petals is deeply cleft into two lobes and bears a pair of scales at the base. The five styles can be seen protruding from the mouth of the corolla in this specimen.

Silene latifolia has a biennial or perennial almost woody rootstock which produces a few vegetative shoots and a few flowering shoots. The lower leaves are about 7 to 15 cm in length and elliptical or oblanceolate (lance-shaped with the narrow end at the base) with the base attenuated into a long stalk. The middle stem leaves are elliptical, and the upper stem leaves narrower and more lance-shaped. The stem is 30 cm to 1 m in height. The whole plant is covered in soft spreading hairs which are slightly viscid (sticky) on the upper stem and sepals. The name 'silene' possibly refers to the moon goddess, from the white flowers, or it may derive from the Greek sialon, 'saliva', from the sticky secretion. The latter is generally considered more likely (not all Silene have white flowers). The species name 'latifolia' means 'broad flower' and the flowers are about 3 cm in diameter.

White Campion is dioecious: there are separate male and female plants. The petals are white or pale rose and open most fully in the evening when the flowers become slightly fragrant. The sepals are fused into a calyx tube with 5 tooth-like lobes at the apex. The calyx is usually pale with 10 indistinct green veins, as in this case. The petals consist of the narrow basal claw and the broadened lamina which is divided into two broad lobes. each petal has two tooth-like scales or auricles where the claw meets the lamina. These scales collectively form a corona or 'crown' guarding the entrance to the flower. The petals ruffle easily in the breeze, which can make photography tricky.

Above: a female flower with five emerging styles. The ovary inflates in pollinated female flowers and develops into a single-celled urn-shaped capsule that opens at the apex by 10 teeth-like valves. The seeds are kidney-shaped and covered in tubercles. Each capsule produces numerous black seeds, each about 1 mm long. (External link: https://www.minnesotawildflowers.info/flower/white-campion).

White Campion occurs on cultivated ground and hedge-banks.

Red Campion (Silene dioica, Silene diurna)

Red Campion is in many ways similar to White Campion except that its petals are a reddish or rose color and the smaller flowers have narrower petals.. However, it can hybridise with Silene latifolia to give S. x hampeana = S. latifolia X S. dioica. These hybrids are very fertile and intermediate and the petals of the hybrid are often pale red or pink. Pale forms of Red Campion also occur, and these may lack anthocyanin more-or-less completely. This complicates determinations. Another useful distinction between Silene latifolia and Silene dioica is in the fruit capsules: in both the capsule opens by 10 teeth at the apex, but in S. dioica the teeth roll backwards in a distinctive manner and the capsule of S. latifolia has a more obvious constriction just below the ring of teeth. Silene dioica also has softer and more flaccid leaves and the shorter, broader calyx is usually tinged red or purple. The hairs on the stem and calyx are slightly sticky (due to glandular secretion).

Red Campion occurs in woods, shady hedge-banks and on rocks by streams. It is a root perennial, growing back from the rootstock each year. It is native to most of Europe.

The specimen shown above and below has sufficient features to be determined as White Campion, Silene latifolia. However, the hybrid between Red and White Campion occurs commonly in areas where both parents species grow and is readily fertile. Thus we might expect to see a continuous gradation in form between the two species due to introgression resulting from cross-pollination between the hybrids and either parent species. In particular, the red coloration of the calyx (sepal-tube) could be the result of introgression from Red Campion. An examination of the fruit capsules might help clarify the determination here. The hybrids usually have some pinkness to the petals, however slight, but that doesn't seem to be the case here.

Sea Bladder Campion (Silene uniflora, Silene maritima)

Found by the sea (on sand, shingle, rocks) and wet rocks on mountains, Maritime Campion occurs naturally in Europe, mainly northern Europe, including Iceland. It is a perennial with an almost woody rootstock.

Each of the five petals has a pair of scales at its base on the inner/upper surface. As the species name uniflora suggests the flowers are usually borne singly at the end of each flowering branch, sometimes in small groups.

Note: another difference with Silene vulgaris is that the petals are broader and overlapping/contiguous in Silene uniflora. The color of the sepal tube is again quite variable.

As a maritime plant, Maritime Campion is largely prostrate (but flowering stems may be ascending to an upright position) and cushion-forming, sheltering it from the drying salty coastal winds. The leaves are also small and slightly fleshy. The plant is quite glaucous (bluish/greyish-green) due to a thick cuticle of waxes. These are maritime adaptations found in many plants that live by the sea.

More Caryophyllaceae

Article updated: 23rd August 2015, 12 April 2021, 17 April 2021