An Exploration of Plants in the Rutaceae / Citrus Plant Family

The Rutaceae plant family, known for its aromatic members, is a diverse group that’s made significant contributions to both amenity horticulture and cuisine.

In this article, we delve into the characteristics, diversity, and notable Rutaceae plants found in Australian landscapes, providing an insightful exploration of native and exotic plants.

Understanding the Rutaceae Plant Family

Characteristics of Rutaceae Plants

Plants in the Rutaceae family typically share a few distinguishing features. They’re often woody, with simple or pinnately compound leaves that are dotted with oil glands, making them aromatic.

The flowers are usually bisexual and radially symmetrical, often brightly coloured and highly fragrant to attract pollinators. Fruits in this family can range from capsules and berries to samaras and schizocarps, providing a fascinating variety within the family.

Diversity within Rutaceae

Rutaceae is a diverse family, encompassing trees, shrubs, and herbaceous plants. These plants cover a broad habitat range, from tropical to temperate regions, and are found naturally across the world, with a high concentration in Australia, South Africa, and South America.

Notable Rutaceae Plants in Australia

Correa spp.

Correa, commonly known as native fuchsia, is a genus of eleven species of flowering plants in the family Rutaceae. Native to Australia, correas are small shrubs that are well-adapted to a variety of habitats, from coastal cliffs to mountainous regions.

With their bell-shaped flowers, hardy nature and tight growth pattern which is perfect for hedging, they’re popular choices in amenity gardens for their low maintenance requirements and year-round interest.

Crowea spp.

Crowea is a small genus of shrubs within the Rutaceae family, known for their glossy foliage and star-shaped flowers. These plants are ideal for rockeries and containers, providing a burst of colour in the garden.

Their low-growing habit and resilience to most pests make them a favourite among landscape professionals.

Flindersia spp.

Flindersia is a genus of 17 species of trees which are celebrated for their striking appearance and hardy nature. They have a wide range of applications in landscape design, from creating shade to serving as windbreaks to working as a feature tree which draws attention.

Microcitrus spp. (Finger Lime)

Finger lime, or caviar lime, belongs to the Microcitrus genus. A native citrus, it’s highly prized for its tangy fruits that are used in a variety of culinary applications, from garnishing dishes to flavouring drinks.

Cultivation of this plant not only provides a unique and delicious fruit but also adds an interesting element to the garden with its thorny branches and small, elongated fruits.

Exotic Members of the Rutaceae Family

Citrus spp.

Citrus species are perhaps the most well-known members of the Rutaceae family, with their fruits being a staple in kitchens around the world. These plants are grown not only for their delicious and nutritious fruits but also for their ornamental value.

Cultivation techniques can vary significantly depending on the specific species and climate conditions, but generally, citrus prefer well-drained soil, plenty of sunshine and a good prune every few years.

Diosma and Coleonema spp.

Diosma species are admired for their attractive foliage and flowers, often used as hedging plants in landscapes. Their fine, needle-like leaves and small, star-shaped flowers make them an aesthetically pleasing choice.

In Australia, the golden diosma is a crowd favourite. This plant is technically in the Coleonema genus, even though we call them diosmas. Both genera are in the Rutaceae family.

Their thin branches can be challenging to prune, often shredding if your hedge trimmer or shears aren’t perfectly sharp or if the blades aren’t flush together. Despite this, with proper maintenance, diosmas can form beautiful, dense hedges.

Murraya spp.

Murraya, also known as mock orange, is celebrated for its aromatic flowers and glossy, evergreen leaves. Its compact growth habit and ability to tolerate heavy pruning make it a popular choice for hedges. In addition to its visual appeal, murraya’s sweetly scented flowers add an olfactory dimension to gardens.

Choisya spp.

Choisya, or Mexican orange blossom, is known for its fragrant foliage and decorative white flowers. This ornamental shrub adds a touch of elegance to any garden, with its lush, green leaves and clusters of citrus-scented flowers.

Cultivation and Care for Rutaceae Plants

Ideal Soil and Climate Conditions

Rutaceae plants generally prefer well-drained soil and a sunny location. However, the optimal soil and climate conditions can vary significantly between species. For example, most citrus trees thrive in warmer climates, while certain citrus plants can tolerate cooler temperatures.

Watering and Fertilising Needs

The watering and fertilising needs of Rutaceae plants can vary greatly. Some, like citrus trees, are heavy feeders that require regular fertilisation, especially during the growing season.

Others, like many shrubs in the family including correas, are relatively low maintenance, requiring only occasional feeding. Regardless of the species, overwatering should be avoided to prevent root rot and other water-related diseases.

Pruning and Maintenance

Pruning requirements will depend on the plant’s growth habit and its role in the garden. Hedges, such as diosma or murraya, should be pruned regularly multiple times per year to maintain their shape and density. Citrus trees require minimal pruning, mainly to remove dead or diseased wood and to allow light into the tree canopy for fruit development.

Tall trees in the Rutaceae family, like Flindersia australis, should ideally be pruned by a qualified arborist to ensure safety and health of the tree. Remember, trees live for a long time and small mistakes can significantly impact their life span and ornamental value.

The Role of Rutaceae Plants in Australian Landscapes

Rutaceae plants play an integral role in Australian landscapes, contributing significantly to environmental sustainability – just like plants in other families. They’re often hardy and adaptable, able to thrive in a range of conditions, making them excellent choices for re-vegetation projects and sustainable garden designs.

Given their diverse nature, Rutaceae plants offer valuable habitat and food sources for wildlife. For example, the flowers of correas and croweas provide nectar for a variety of birds and insects, while the fruits of citrus trees are a food source for many bird species.

In terms of landscape design and architecture, Rutaceae plants offer a wealth of options. From the fragrant murraya and choisya used as hedging plants to the towering flindersia trees that provide shade and structure, these plants add both aesthetic and functional value to landscapes.

It’s important to note that both native and exotic Rutaceae plants contribute positively to biodiversity. While locally endemic plants are adapted to local conditions and fauna, exotic plants can add diversity and interest to a garden, often providing different flowering times or growth habits that extend the range of habitats available in a given area.

Our native generalist pollinators are very happy to feed from the flowers of exotic Rutaceae plants, just like they are for our native Rutaceae members.

Daniel’s Wrap

Throughout this exploration of the Rutaceae plant family, what stands out is the incredible beauty, aromas and ecological value these plants offer. From their olfactory foliage and vibrant flowers to their resilience and adaptability, Rutaceae plants hold immense appeal for both home gardeners and professional landscapers.

As we deepen our understanding of these diverse species, we can better appreciate their contributions to our gardens, landscapes, and broader ecosystems. Whether it’s the humble correa providing nectar for birds or the exotic citrus tree offering its bounty of fruits, each member of this family plays a unique role in enhancing our environment.

So, let’s celebrate and make more use of the Rutaceae plant family in our gardens and landscapes. By doing so, we not only enrich our own gardening experience but also contribute to the health and diversity of our local ecosystems.