Citropsis gilletiana aka Gillet's Cherry Orange

Citropsis gilletiana is an evergreen tree. It belongs to the rue family, Rutaceae. Its common name is Gillet's cherry-orange. It comes from west-central tropical Africa. Its range includes the Democratic Republic of the Congo. PFAF places it in the country's northeast. Kew links the species with a wet tropical climate. These sources do not state its exact wild habitat. Useful Tropical Plants notes that people grow this species.

The tree grows about 26–33 feet [8–10 metres] tall. PFAF gives a garden size of 30 feet [9 metres] tall and wide. It lists a medium rate of growth. PFAF calls it the largest member of its genus. It also says it grows with the most vigour. Thin spines grow along the stems. They are about 0.07–0.16 feet [0.02–0.05 metres] long. The sources give no more facts about bark or leaf shape. They do not describe the flowers or say when they bloom.

The round fruit turns yellow. It measures about an inch across. Its harsh taste makes it unfit to eat. PFAF gives the species no food-use rating. Neither PFAF nor Useful Tropical Plants lists a use as medicine. Both sources list no known hazards. This does not mean the plant is safe. That hazard listing does not change its lack of food value.

PFAF says to grow it in sun, not shade. It needs moist soil that drains well. The tree can grow in sand, loam, or clay. Soil can be mildly acid, neutral, or mildly alkaline. PFAF lists USDA zones 10–12. These fit its tropical range. The sources list seed as the means to grow new plants. They give no detailed steps for sowing. They give no care plan for each season. Nor do they support a specific use for show in gardens.

Its main recorded value is as a citrus rootstock. This forms the roots beneath a grafted tree. Reports from Congo say it resists foot rot linked to Phytophthora citrophthora. They also say it resists a Monohammus longhorn beetle. The beetle's larvae harm the lower trunk of prone citrus trees. Trials used this rootstock for sweet orange and mandarin. They also used it for grapefruit and lemon. Those grafted trees grew more strongly than trees on sour orange roots. The reports stress the need to keep the graft high enough. This helps avoid infection from the soil. These findings cover only the named threats. They do not show that it resists all pests or diseases.