The Different Shapes of Indoor Fern Leaves
An astonishing variety of shapes
Ferns do not produce anybut they more than make up for this lack with their enormous range of different shapes of growth and leaves.
The shapes of growth are so many that this alone makes it possible to produce countless variety when growing ferns as indoor plants.
• upright, like Arachniodes adiantiformis
• elegantly drooping, like maidenhair fern (Adiantum)
• hanging, like Adiantum caudatum which is excellent for hanging containers, epiphyte trunks or for creating a fern pillar
• climbing, like Lygodium which can be trained up sticks or posts
• tree-like, like several types of hard fern () which form small trunks in old age, not to mention the huge tree ferns whose trunks can grow to a height of 20 m (67 ft).
The shapes of the leaves also show a great range of different forms and variations. Besides the classic palmfrond-shaped leaves, as displayed by species of Nephrolepis, there are the undivided leaves of bird’s-nest fern (nidis or antiguum) and of many other species. In direct contrast, one can also find very finely feathered leaves, as with individual forms of maidenhair fern (Adiantum) or sword fern (Nephrolepis).
The plants of some genera develop two kinds of leaves. This is called heterophyllia. First, young leaves develop which usually have wider fronds and shorter leaf stalks. They have noand are, therefore, sterile. With increasing maturity, the plant later produces spore-bearing, fertile fronds, often on longer stalks, as with ribbon fern ( ), and which stand stiffly upright and possess many narrow fronds, as with hard fern ( ). Among other genera, like royal fern (Osmunda), which are grown as outdoor plants, special fronds are produced which bear spore capsules.
The arrangement of spore capsules on the leaf undersides is also very varied and can be an important distinguishing feature in determining the species of a plant. The spore capsules may be grouped together in round, long, kidney-shaped, urn-shaped or striped formations. These are called sori.
What is a frond?
Fronds are the very finely divided leaves of ferns, which consist of many small feathery sections which grow from one central leaf stem, rib or rhachis.
Single-feathered (pinnate) fronds are single, undivided feathery leaves growing from the main leaf rib; for example, Nephrolepis.
In double, triple or multi-feathered fronds (bipinnate), the feathers are divided two or more times. Examples includetsus-simense (double), Davallia trichomanoides (three to four divisions).
Divided fronds: Here the division of the leaf does not reach quite as far as the central leaf rib. Example:aureum.
Other shapes of leaves: Ferns also occur with hand-shaped, divided fronds (pedata) or with coarsely lobed leaves (Platycerium). Undivided leaves frequently occur among or .
Ferns are not only green
By appearing in all shades of green, ferns more than make up for their lack of brightly coloured flowers. If you look at them a little closer than most people do, however, you will also discover a discreet and surprising variety of colours among the plants themselves.
Leaves and stalks:
The most conspicuous are variegated, patterned in green-white, green-yellow or green-red and often with striped fronds. Sometimes the young leaves will be light green or reddish when shooting. The spectrum of colours on stalks can range from yellow to green and brown to black. Either the stalks themselves will display these colours or they will bear brown, sometimes even silvery, scales.
Some ferns produce creeping rhizomes, either below or above ground, that may be covered in whitish, yellow, golden brown or red brown scales which make an interesting, eye-catching spectacle.
The groupings of spores on the undersides of leaves may also be quite attractive. These sori are often creamy white in their unripe state and change colour to become brown when they are mature. Different species possess conspicuously coloured spore capsules; for example,aureum. This fern is known for its round, golden yellow clusters of spores. Black stripes made up of lines of spores create interesting contrasts on white and green striped fronds as formed by many species of ribbon fern ( ). In the case of Pteris cretica “Albolineata” these parts of the plant are like graphic works of art. The spores themselves are black, brown, grey or yellow, but even ferns with green spores are known, for example Platycerium wallichii.
Ferns do not form flowers and seed but they still manage to reproduce. Reproduction proceeds through two completely separate phases termed ‘alternating generations’. During the non-sexual phase, spores are formed on the undersides of the fern fronds. The spores germinate and produce a prothallus which, in turn, forms male and female sexual organs on its underside, which then begin a sexual phase. Provided conditions are favourable, this is the phase when fertilization takes place and a new fern plant is created.
How ferns became fashionable
There is evidence from as early as the first half of the seventeenth century that ferns were being cultivated in Europe. The tropical ferns often grown today were mostly introduced to Europe from the end of the eighteenth to the middle of the nineteenth century. They were often transported in a special glass box called a Wardian case, invented by a British doctor named Nathaniel Ward. This sealed glass tank can be seen as the forerunner of theand various indoor glass display cases.
Glass cases and enclosed plant picture windows were very popular in the second half of the nineteenth century and enabled the successful cultivation of ferns, orchids and other tropical plants. In keeping with the prevailing fashion of the time, large, elaborately decorated containers were constructed to grace the salons of the wealthy middle and upper classes. In our present-day small flats and houses with their restricted space, we mostly have to manage without such an ideal “home” for our tropical fern species.