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Products > Castanospermum australe
Castanospermum australe - Moreton Bay Chestnut
Image of Castanospermum australe
[2nd Image]
Habit and Cultural Information
Category: Tree
Family: Fabaceae = Pea Family
Origin: Australia (Australasia)
Evergreen: Yes
Flower Color: Red & Yellow
Bloomtime: Summer
Height: 40-60 feet
Width: 30-40 feet
Exposure: Full Sun
Irrigation (H2O Info): Medium Water Needs
Winter Hardiness: 25-30 F
May be Poisonous  (More Info): Yes
Castanospermum australe (Moreton Bay Chestnut) - A slow growing evergreen tree to 25-40 feet tall with gray knobby and shallowly fissured bark and a round headed to flat topped crown. The large pinnate leaves have 11-15 luxurious emerald green leathery leaflets that each can be up to 6 inches long. Red and yellow pea-like flowers bloom from all branches in summer - blooms best in areas that have some summer heat but we get a regular show along the coast in Santa Barbara. Following flowering appear the thick cylindrical seed pods that are up to 10 inches long and contain five large round brown chestnut-like seeds. The seed pods dry to brown in fall before splitting open to drop the seeds in early winter.

Plant in full sun to light shade with occasional summer watering - surprisingly drought tolerant in coastal gardens and is hardy to 25 degrees F. It is a suitable lawn tree or can grow in a drier situation. Roots don't lift pavement so is also a good for use as a patio or street tree, but roots will seek out water so not best planted near old clay leaky sewer lines or septic leach fields. The flowers produce an abundance of nectar, making them very attractive to hummingbirds. This is a pretty tree even when not in bloom, so it can be planted in more coastal gardens, where flowering is less assured, just for its foliage and occasionally it is even grown as an interior house plant or a curiosity plant because of its large seed, then sometimes called "Lucky Bean Plant".

Castanospermum australe is usually called Moreton Bay Chestnut, named for the bay in Brisbane, Queensland Australia, which is one location where this plant grows naturally in Australia, but it can also be found in coastal rainforests and along beaches from New South Wales north along the Queensland coast and west of there in the warm subtropical Bunya Mountains of Queensland and on the South Pacific island nations of New Caledonia and Vanuatu. The plant was first discovered then later officially described by Kew botanist Allan Cunningham in 1829 with the name for the genus coming from the Latin name 'castanea' used for the Chestnut and the Greek word 'spermum' meaning "seeded" in reference to the large chestnut-like seed (which raw are poisonous!) and it is because of this seed that another common name is Black Bean. The specific epithet is from the Latin word 'australis' meaning "southern" in reference to this plant being from the southern hemisphere. In Australia this tree is considered a valuable timber species and its seeds were used for food by the Aboriginal people after extensive preparation to remove toxic compounds. More recently researchers have been interested in it because of the alkaloids they contain, which are potentially useful in the treatment of HIV and cancer.

One of the best, and largest specimens in California is at the Huntington Botanic Garden and this tree measured in 2024 at 49 feet tall is now listed on the California Big Tree Registry. Nice plants can be found growing around Santa Barbara there are a couple street trees on Oak Park Lane and a specimen at the Stow House in Goleta that was reportedly planted in 1883 and it is thought to be the first one planted in the Santa Barbara area. We have grown this attractive tree since 1984. Image on this page courtesy of Ken Greby. 

This information about Castanospermum australe displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.