Donnerstag, 11. Oktober 2012

The Caryophyllaceae - an introduction

In today's article, I want to show you the Caryophyllaceae („Nelkengewächse“ in German), which are one of the major plant families in Middle Europe. The goal of this article is to give you a general overview about this family, its systematic and the characteristic features.

1) Systematic & General Information

The family includes 86 genera with 2200 different species. Most of them are herbaceous or perennial plants, but there are also shrubs, sub-shrubs or even liana. However, the “typical” plant from the Caryophyllaceae is a herbaceous plant, which reaches heights between 50 and 100 centimeters in average.

Caryphyllaceae - flower diagram with apparent breach
of the "Rule of Alternation"

In the most cases, the leaves are narrow to lanceolate with a smooth margin. They are sitting directly at the stalk or have only a very short petiole. Usually, they are arranged in a decussate leaf-pattern. Moreover, the nodes are swollen.

However, the most distinctive feature of the Caryophyllaceae are their flowers and the inflorescences. The inflorescences are often panicles with cymes in the axillary (instead of single flowers). In Botany, such a composed inflorescence called Thyrse

Shematic construction of a thyrse

The formula of the most flowers is *K(5) C5 A5+5 G(5): five fused sepals, five free petals, two circles of stamen with five stamens per circle and five fused and epigynous carpels. But this is only the basic formula, which may very significantly (see point 2)). The Calyx is also much larger then the crown.

The stamens are also arranged in a unique way. The outer circle is inwardly offset. Thus it seems as if the stamens are breaking the Rule of Alternation, because the stamens of “outer” circle, which are in fact the stamens of the inner circle, are not alternating to the petals.

the kinked flower is typical for the Silenoideae
(here: Dianthus agg.

Primary pollinators are insects, most of them butterflies (Entomophily). For this reason, the flowers of the Caryophyllaceae are adapted to their pollinators and are designed as a large landing area. Such a flower is also called plate flower.

The ripe fruits are capsules but also berries and nuts.

All plants from the Caryophyllaceae contain Anthocyanids. This is a little bit curious, because the Caryophyllaceae belong to the order of the Caryophyllales (along with the Chenopodiaceae, Portulacaceae. Armaranthaceae) and the unique feature of this order is the content of Betalains within the plants.

betalains are characteristic for the Caryophyllales
.... but not for the Caryphyllaceae

Betalains are natural dyes (along the Anthocyanides and the Carotenoids), which are also responsible for the red color of Beetroot (Beta vulgaris). The Caryophyllaceae are one of only two families of the order without Betalains (the other family are Molluginaceae, which are native to South Africa).

2) Subfamilies and their differences

In most literature, the Caryophyllaceae are subdivided into three large subfamilies: the Silenoideae (which are the largest one), the Alsinoideae and the Paronychioideae.

  • Silenoideaa: This is the largest subfamily, which includes genera like Silene, Saponaria or Dianthus. Typical for the Silenoideae are the fused sepals of the Calyx and the kinked petals. Flower formula: *K(5) C5 A5+5 G(5)

    Silene latifolia Mill.

    Dianthus agg.

    Saponaria officinalis L.

  • Alsinoideae: The sepals of species from this subfamily are free. The petals are not kinked but deeply lobed. Thus it appears as if the flower has ten petals. Typical genera are Stellaria, Minuartia and Arenaria. Flower formula: K5 C5 A3+5 G(3)
Stellaria holostea L. - here, you can see
the depply lobed petals

Cerastium tomentosum L.
  • Paronychioideae: This is a very small subfamily with only a few genera and species (like Spergula or Hemiaria). In the most cases, the petals are missing. Another distinctive feature are stipule. Species from the Paronychioideae are the only Caryophyllaceae with stipules. Flower Formula: * K5 A5+5 G(5)

So, I hope that I was able to give you a general overview about the Caryophyllaceae. Maybe, they are not the largest or the most complex family within the vegetable kingdom, but they have some interesting features and are easy to recognize.

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