Australian Rainforest Seeds

A Guide to Collecting, Processing and Propagation

Mark Dunphy, Steve McAlpin, Paul Nelson, Michelle Chapman, Hugh Nicholson

• Publisher: CSIRO PUBLISHING
• Year: 2020
• ISBN:
  9781486311521
• Topic: Scienze biologiche
• Subtopic: Orticoltura

Have you ever wondered how to grow your own rainforest trees? Is there a beautiful tree that you have always wanted to collect and propagate the seed from? Are you in the business of ecological restoration, rainforest propagation or environmental education?

This long-awaited guide to rainforest seed propagation unlocks the secrets to growing 300 rainforest species. Providing specific information on how to sustainably collect, process and germinate seeds, this user-friendly book aims to support a growing movement of rainforest restoration.

With invaluable information based on 30 years of research in northern New South Wales, users will find even difficult rainforest species delightfully easy to grow. Seeing a seed germinate, caring for the seedling and eventually planting the tree is deeply satisfying. And, in this time of widespread deforestation, millions of trees are needed for restoration and every tree counts. Whether you are growing one or one hundred thousand, why not start today?

1 Introduction

There is something primal about gathering fruit from wild trees. It is an act carried out over millions of years by thousands of species, including humans and our close primate relatives. Even today, humans walking around in the rainforest sense this history and find it irresistible to pick up a fruit and ponder its potential. For some the fruit represents food, but for others it is about the almost magical possibility of the small seed within growing into a huge tree.

Aboriginal people have collected fruits from rainforest plants in Australia for tens of thousands of years. Over this time, they developed an intricate and detailed knowledge of what to collect, when to collect and how to prepare rainforest fruits. Following colonisation, rainforest clearing and dispossession, this information either remains in the hands of a few or has been lost. Despite this, some information has survived. For example, we know that Foambark (Jagera pseudorhus) was used to ‘stun’ fish, the Black Bean (Castanospermum australe), properly processed to remove its poisonous toxins, could feed hundreds at ceremonial gatherings, and the sweet cinnamon flavoured Midyim (Austromyrtus dulcis) berries were picked and eaten. Although Aboriginal collection of rainforest fruits has been mostly about food and medicines, and not so much about propagation, there is considerable overlap in relation to knowledge of the timing of fruit and seed production. It is tragic to think of so much knowledge lost, and that there has not been a continuous flow and exchange of knowledge through time.

Most of the subtropical rainforests of New South Wales and Queensland were cleared in the mid to late 1800s and early 1900s. However, logging of rainforest continued well into the 1980s. Since that time there has been a growing interest in regenerating rainforest, and that interest has developed into a highly skilled and experienced industry that is restoring and replanting hundreds of hectares. This book aims to fill a gap in the body of knowledge on rainforest restoration by passing on skills and information to allow more people to collect and propagate rainforest plants in a sustainable way. At current levels alone, the restoration of rainforest from cleared and degraded land needs tens of thousands of rainforest plants to be propagated, grown, planted and maintained every year. To expand this planting rate, we need hundreds of thousands of rainforest plants every year. To supply these plants, many nurseries – commercial, community and backyard – are needed to play the vital role of propagating seeds and producing plants.

Subtropical rainforest in Terania Creek, New South Wales

There are no texts specifically dedicated to the collection, processing and propagation of subtropical rainforest plants. This book is the first, and is the culmination of 30 years of research, experience and practice at the Firewheel Rainforest Nursery, situated within the former Big Scrub rainforest in northern New South Wales. Even with 30 years of work, this book does not have all the answers. There are still many unsolved mysteries and secrets to germinating rainforest seeds. It is hoped that this book is the start of a continuous process of sharing research, knowledge and discoveries that will help increase plant numbers and protect and enhance the biodiversity of the rainforests into the future.

2 Biology and ecology

Is this a seed, a fruit or a nut? It may come as a surprise to know that it is possible to be holding all three. Indeed, a nut is a type of fruit, with a hardy woody inner layer that usually contains one seed. Seed collecting, processing and propagation requires a basic understanding of seed biology and terminology. Knowing the parts and functions of fruits and seeds can assist identification during collecting, prevent seed damage during transport and processing, and reduce germination time during propagation. It is also helpful when communicating with colleagues or other propagators during discussions about which processing techniques may be most beneficial.

What is a flower?

There are many ways the various flower parts can be arranged to create the structure we recognise as a flower, and these differences provide taxonomists with ways to differentiate between families. However, similar-looking flowers can be found in families that are not closely related.

A flower is the reproductive organ of any angiosperm (flowering plant) and is positioned on a pedicel (flower stalk), with an expanded end called a receptacle that supports whorls of flower parts. The two whorls closest to the receptacle are collectively called the perianth, made up of the sepals and petals. The sepals are usually green and enclose the bud. The petals can be white or coloured, and rarely can even be green. When the sepals and petals are similar in size, texture and colour then they are all termed tepals or perianth parts. The next inner whorl consists of stamens, part of the male reproductive organ, which produce pollen. The last whorl is called the pistil, the female reproductive organ, which consists of one or more carpels. Each carpel is made up of an ovary (base), style (stalk) and stigma (top). The stigma receives the pollen, which travels down the style to the ovary. Each ovary contains an egg cell (ovule) and is connected to the placenta (ovary wall tissue) by a funicle (stalk). Each fertilised ovule becomes a seed, and the ovary tissue becomes the surrounding fruit.

Parts of a simple flower – Macleay Laurel (Anopterus macleayanus)

Cone – Shining Burrawang (Lepidozamia peroffskyana)

Gymnosperms (non-flowering plants) have slightly different reproductive structures. Fertilisation occurs when wind-borne pollen grains from male pollen cones are collected on the stigmatic surface of scale-like leaves, on the ovulate cones. The pollen grain matures into sperm inside the ovule and then fertilises the egg, which together develop to form a ‘naked’ seed, so called due to lack of protective fruit layers.

What is a fruit?

In angiosperms, the fleshy material surrounding a seed or seeds is called the fruit. In gymnosperms (non-flowering plants), the seed-bearing structure is the cone, consisting of multiple cone scales, each bearing a seed. In addition, some gymnosperms do have fruit-like structures to attract flying seed dispersers (e.g. species in the family Podocarpaceae).

Simple fruits develop from single flowers with a single carpel and ovary. Aggregate fruits develop from single flowers, with two or more separate or partially united carpels that develop into several separate fruits bunched close together. Multiple fruits consist of united fruits developed from many flowers positioned closely.

Simple fruit – Hard Quandong (Elaeocarpus obovatus)

Aggregate fruit – Native Mulberry (Hedycarya angustifolia)

Multiple fruit – Cockspur Thorn (Maclura cochinchinensis)

Fruit tissue, or the pericarp, consists of three layers: the exocarp (outer layer), the mesocarp (middle layer) and endocarp (inner layer closest to the seed coat). Sometimes the layers are not distinct, or two layers are blended together, while in other fruits the three layers are clear. For example, in a peach, the exocarp is the f...