Clusia is a large genus of trees and shrubs native to tropical America characterized by their branches, which grow horizontally, and their leaves, which are thick and tough. There are about 150 Clusia species, but Clusia rosea, or the autograph tree, is the only one commonly grown. It is notable for its tendency to grow on top of and strangle other plants. It is an invasive species. Another unusual quality, this species is part of the only genus of plants capable of absorbing carbon dioxide at night.
The tree has stiff, dark green or olive colored leathery leaves that grow to about 8 inches long. These leaves are tough enough that they can be carved into, hence the common name “autograph tree.” It also blooms pink or white flowers in long flower heads during the summer and small green fruits that ripen to black and eventually split open to reveal bright red seeds. These seeds are very attractive to birds and other fauna.
- Botanical Name: Clusia rosea
- Common Name: Autograph tree, copey, balsam apple, pitch apple
- Plant Type: Perennial evergreen
- Mature Size: Can grow up to 25 feet tall
- Sun Exposure: Full sun
- Soil Type: Sand, clay, loam; well-draining
- Soil pH: Slightly acidic to neutral
- Bloom Time: Summer
- Flower Color: White or pink
- Hardiness Zones: 10 to 11 (USDA)
- Native Area: Caribbean
How to Grow the Autograph Tree
The autograph tree tends to spread out fairly wide as it grows. It should be pruned about once a year, in early spring, to keep it nicely formed. Fertilization will help C. rosea grow fully, and it should only be kept outside in tropical areas. The plant makes an excellent hedge because of its thickness and low maintenance level, and if you grow it as a tree you can also underplant things close to the tree base.
Full sun is best, but it can tolerate partial shade as well. When it is grown indoors as a houseplant, it will cope with medium light levels and some degree of shade.
A sandy, soft and loose well-draining soil is best. It should be rich in organic matter, fertile, and mixed with a small amount of soil for orchids. The heavy foliage is salt tolerant; this species can be grown in exposed positions near the ocean coastline.
The autograph tree should be watered regularly for the first year or so until the plant is fully established. You can scale back its water after that, although regular watering will help it grow more fully. This species is fairly drought-tolerant, but you should never let the soil get completely dry.
Temperature and Humidity
This plant thrives in warm, tropical conditions. It prefers average to warm household temperatures between 60 and 85 degrees Fahrenheit. This plant will not tolerate cooler temperatures below 50 degrees Fahrenheit. Clusia rosea prefers high humidity. If you have an indoor container plant, you can place it on a shallow gravel tray filled with water and mist regularly.
Fertilize three times per year in the spring, summer, and fall. Use organic, granular fertilizer. Or, you can fertilize more frequently but must use an evenly balanced diluted liquid fertilizer.
Toxicity of the Autograph Tree
According to the Food and Drug Administration database of poisonous plants, Clusia rosea made the list. Birds eat the seeds and are a main propagator of this tree species, but the green fruits are mildly poisonous, as are the leaves. Both fruit and sap will cause severe stomach and intestinal irritation, vomiting, and diarrhea if ingested. Keep pets and children away from this plant, as the fruits may tempt them. The sap may also cause skin allergies in some people; it is a good idea to wear gloves when handling the plant.
Potting and Repotting
Due to its quick growth, C. rosea can often overgrow its container. Lift the root ball out as a whole and replace it in a larger container that can accommodate the root system. As the plant matures, it may become too large to be kept in containers at all unless it is well-pruned. If so, it can be moved outside and used as an ornamental tree or hedge.
Propagating the Autograph Tree
C. rosea is a hemiepiphyte. It begins its life as an epiphyte—growing on another tree or structure—and then plants itself in the ground once it reaches it. Notably, this tree overgrows and eventually chokes its host tree to death with its roots after it reaches the ground, which has made it a dangerous invasive species in several tropical countries.
The tree can propagate fairly easily by seed or by cuttings. To propagate by cuttings, simply sever the stems and replant in the warm wet soil to allow them to root. This is a fast-growing and hardy plant that is quite easy to propagate, especially in containers.
Varieties of the Autograph Tree
C. rosea is the only member of the Clusia genus that is commonly grown, though other Clusia species are cultivated in botanical gardens. It behaves similarly to several strangling vines like the strangler fig (F. aurea) and the bearded fig (F. barbata), but the resemblance is superficial.