It is hard to believe that the rain forests of the Amazon can be very dry places. Of course during the rains vast areas of low-level rain forest can be flooded for hours or days, but in the end it all drains fairly rapidly into a vast network of creeks and rivers, and eventually to the sea. In a surprisingly short time the ground under the canopy becomes dry again. I have waded for many days through what is normally dry ground during the rains. However when it finally drains away progress can be fairly quick, but there remains a substantial amount of standing water above ground level which is vital to the existence of many forms of animal and plant life. Thousands of small streams originating from the Roraima massif course their way through the thousands of square miles of forest, but the standing water is mainly provided by plants of the bromeliad family. The Natural Order Bromeliaceae contains over 2000 species, and most of them are epiphytes (tree dwellers) although quite a number are terrestrial. Most of the epiphytic bromeliads collect their water in urn-shaped leaves designed to collect and save water which gives life to thousands of different insects, rare frogs (particularly found in Trinidad) and plants such as the Bladderwort (called Utricularia humboltii) found on Mt.Roraima. In other parts of the world the ability to store water results in important adaptations to dry conditions and the means which enable plants to survive as found in the Cactaceae.
In Guyana we have many fine plants called Ravenala madagascariensis, commonly known as the Traveller’s Palm. It is not a true palm, but a member of the banana family. Many people think it has the name Traveller’s Palm because it generally (though not always) arranges its leaves on an east/west axis in order to catch most of the sunlight during the day. I believe that its name arose because like the bromeliads it is also a source of water which is collected in the leaf bases, each of which holds a good gallon. It is used as a watering hole by birds and monkeys, both of which travel for many miles in search of water. When the leaves of the Traveller’s Palm finally start dying off and fall naturally below the horizontal, the stored water runs out of them and onto the ground, and a surprisingly large number of seeds which have been carried by birds and monkeys from plants some little distance away pour out as well. This seed germination indicates the distance travelled by their depositors.
This brings me nicely to the question of seeds and their germination, an absolutely fascinating subject. Whilst most seeds can be sown normally and covered lightly by soil afterwards, not all seeds respond in the same way. For example, everyone on the planet can germinate fresh lettuce seed and mustard and cress in just a few days. Especially here in Guyana. But you can hang around for ages waiting for the seed of Australian Gum (Eucalyptus species) and South African Protea to germinate. The seeds of these two plants are as hard as old boots. Harder in fact, and this always provides entertainment to gardeners having fire-raising tendencies. The reason is that in nature the job of cracking open seed coats is often done by bush or veldt fires passing quickly over the ground. In the potting shed the seed of eucalyptus, proteas, and the canna (very common in Guyana) can be cracked by placing them in a small ball of tissue paper and setting fire to it. This simple act is normally sufficient to get cannas cracking. For the faint hearted, chipping the hard seed coat with a knife on the other side of the ‘eye’ is effective as well, if not so much fun. Other types of seed can have their germination helped by soaking them in water for a few hours before sowing. Seed from the pea and bean family will swell up very quickly when placed in water. When this happens they have to be planted very quickly so that they do not dry out. An old and revered friend of mine, a wonderful gardener called Lou Stenning and my predecessor as curator of the Tropical Department at the Royal Botanic Garden, Kew used to sow very fine seed of orchids and nepenthes, one of the Pitcher plants from Borneo, in an interesting and highly successful way. He filled pots with sphagnum moss and old orchid compost comprising mainly osmunda fibre packed as tightly as possible. He then stretched a piece of old silk or nylon stocking very tightly over the top of the pot and sowed this seed onto the surface. The moss-filled pot stood in shallow water provided constant moisture, and the texture of the material was fine enough to hold this very fine dust-like seed. Germination was always excellent. The next time I talk to you will be in December. Until then may your God go with you.