Flowering, fruiting and monocots

Skyrail Nature Diary: September 2012

September is normally the start of the main flowering event of the year as it's quite near to the end of the dry season. The plants are attempting to have their fruits ready by the time the rain turns up. If the weatherman is right and we will be experiencing a new cycle of El Niňo, this familiar pattern will most likely be a little upset. We will see flowering and fruiting literally out of season. The only other time we see this phenomenon is immediately after a cyclone. There are several trees fruiting at the moment, the most common of which is the Kuranda Quandong. These trees grow up to 30 metres tall and are often buttressed. The flowers are cream and hang under the branches. The fruits are large drupes with dry green fruit flesh. The husk inside looks like a rugby ball and has very thick walls. The edible kernel is very hard to extract but well worth the effort. These fruits were one of the staples of the Djabugandjii diet. They often used a special nut stone to open the husks. Another tree fruiting at the moment is the Yellow Almond (Emmenosperma cunninghamii: Rhamnaceae). These dark leaved trees grow up to 25 metres and also may be buttressed. The flowers are tiny and yellow as well as very inconspicuous. The fruits are small yellow drupes that split open to reveal the reddish seed inside. The seed remains on the tree for a very long time.

Red Ash is now flowering along the cableway. These beautiful pioneer trees grow up to 30 metres and may be moderately buttressed. A pioneer tree is a tree that grows very fast when a gap occurs in the rainforest and have very short life spans. The canopy (the top of the tree) is very simple and flat and there is very little branching. The dark leaves have distinctive white undersides. Small clusters of orange flowers are very obvious to even a casual observer when they are around. The fruits are small black capsules that look like a woody cup with a small ball shaped seed in it.

Monocots are one of two main branches of the flowering plants. Unlike the dicots (a possibly unnatural group) the monocots don’t have secondary growth, which means that they never turn into real trees that expand in girth. At best they grow into tall herbs that resemble trees such as palms and pandans. There are a number of easily observed differences between monocots and dicots. First of all monocots germinate with only one seed leaf while dicots germinate with two. Monocot leaves have simple veins that don’t branch like a typical leaf does. The monocots have no tap-roots, their roots being a simple cluster with no main dominant root. Monocot flowers are organised in multiples of three whilst dicot flowers are organised in fours, fives and sevens. The least obvious characteristic of the monocots is the organisation of their water and sugar vessels. In monocots they are organised in random clusters in the trunks whilst in dicots the vessels are organised in an outer ring. The latter is best seen in trees that have been felled. Several important groups of flowering plants are monocots. Grasses make up a lot of the vegetation in drier areas of the world and are the dominant plant in savannahs. Sedges are the grasses’ watery counterpart. Many have hollow stems full of white hairs to enable them to float. Those that don’t float tend to favour wet areas a little away from the water’s edge.

Bulrushes are a special kind of sedge with large sausage shaped structures on the top of the stem. Irises are a popular plant in many temperate gardens of the world thanks to their beautiful flowers which are often blue. Pandans are palm like monocots that often favour swampy areas. They have strap like fronds with spiny edges. The fronds were often split and used for weaving by the Djabugandjii. The fruits are generally borne on thick stalks and are often quite large structures that are hard to break open. Some, like the Scrub Breadfruit have prickly fruits with strongly acidic fruit flesh that is nonetheless edible. Monocots are not primitive flowering plants despite their often simplified structures. Several are pioneers that are among the first colonisers on newly disturbed areas. Most produce copious numbers of offspring that give them a distinct advantage when it comes to recovering after the loss of large numbers of individuals.

 Palms (Arecaceae) are without a doubt the most famous monocots, at least as far as the image of the tropics goes. Palms have huge root balls and often long pseudo-trunks. They can be either solitary of clumping. Solitary palms have one trunk and are unable to regenerate if they lose their crowns. Clumping palms have multiple trunks and a much larger growth centre than solitary palms. This means that any trunks that are ripped out or chopped will usually be replaced. Anyone who owns one or more Golden Canes from Madagascar know this all too well. The fronds are in essence giant leaves. All palm flowers are tiny and have no petals. Palm fruits are more varied and some are even edible. The most obvious edible palms are the Date Palm and the Coconut, the latter is also important in the production of palm oil. The largest palm fruit is produced by the famous Coco de Mer of the Seychelles. These palms resemble coconuts but have a much larger double fruit.

Orchids are very popular plants due to their exquisite flowers. The main character that defines orchids is the fused male parts of the flowers. Orchids can be ground plants, epiphytes or parasites. As epiphytes, orchids are in essence succulents due to the difficulty of obtaining water in the tree tops. Together with the epiphytic ferns orchids are the most important epiphytes in Australian rainforests. The epiphytic orchid’s roots contain symbiotic fungi that collect minerals directly out of the air. At Skyrail's Red Peak station the King Orchid was in flower last month. The most obvious ground orchid at Red Peak is the Christmas Orchid. Ironically the parasitic orchids grow in the ground and are parasites on a fungus. They have no chlorophyll.

Lilies are another popular flower in people’s gardens around the world. The flowers are often large and have generally six petals and stamens. The best known one is the Schelhammera which grows at Barron Falls station, most noticeably under lookout three. Schelhammera is quite tiny and grows in clumps in well drained areas where it doesn’t rain too much. Most tourists never get to see them in flower but luckily the new Djabugay Aboriginal guided rainforest walking tours at Barron Falls have the flowers on their signs.

by Tore Lien Linde