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 other plants (often strangling them). It is widely considered to be an invasive species. Another unusual quality, this species is part of the only genus of plants capable of absorbing carbon dioxide at night.
The autograph tree has stiff, dark green or olive-colored leathery leaves that grow to about 8 inches long. The leaves are tough enough that they can be carved into, hence the common name “autograph tree.” It has long flower heads with pink or white flowers that bloom in the summer, followed by small green fruits that ripen to black and eventually split open to reveal bright red seeds. The seeds are very attractive to birds and other fauna. The autograph tree is commonly grown as an indoor plant. Where it is able to survive outdoors—in zones 10 and 11—it can be planted in spring or fall.
|Botanical Name||Clusia rosea|
|Common Name||Autograph tree, copey, balsam apple, pitch apple|
|Plant Type||Perennial evergreen|
|Mature Size||8 to 10 feet tall and wide (can reach 25 feet tall as a tree)|
|Sun Exposure||Full sun|
|Soil Type||Sand, clay, loam; well-draining|
|Soil pH||Slightly acidic to neutral|
|Flower Color||White or pink|
|Hardiness Zones||10 to 11|
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 it grow fully. The plant makes an excellent hedge because of its dense growth habit and its minimal maintenance needs. Alternatively, if you grow it tall as a tree, you can underplant things close to its base. The autograph tree is salt-tolerant and can be grown in exposed positions near the ocean.
Grown as a houseplant, the autograph tree needs warmth, humidity, and a moderate amount of sunlight daily. A room with a south- or west-facing window is ideal for giving it a few hours of bright sun plus some indirect light and some shade.
Full sun is best, but this plant 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, loose, well-draining soil is best. It should be fertile and rich in organic matter. When growing in pots, blend the potting mix with a small amount of growing medium for orchids.
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. Autograph tree houseplants typically need water once a week in summer and three times per month in winter.
Temperature and Humidity
This plant can be kept outside only in tropical areas, as will not tolerate temperatures below 50 degrees Fahrenheit. Indoors, it prefers temperatures between 60 and 85. It also 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.
Potting and Repotting
Due to its quick growth, C. rosea can often overgrow its container. To repot, lift out the root ball as a whole and move to 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 the climate is suitable, large plants can be replanted outdoors.
Propagating the Autograph Tree
C. rosea is a hemiepiphyte. It begins its life as an epiphyte—a plant that grows on another tree or structure without being parasitic—and grows toward the ground until it eventually plants itself in the soil. Over time, it overgrows and eventually suffocates its host. This growth pattern is what has made the autograph tree a dangerous invasive species in several tropical areas.
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.
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 irritate the skin for some people; it is a good idea to wear gloves when handling the plant.