Question

Deciduous and extremely freeze hardy true citrus species is

• A. Poncirus
• B. Eremocitrus
• C. Microcitrus
• D. Clymenia

Hint:

Most common citrus fruits (oranges, lemons, etc.) are evergreen and subtropical. Poncirus trifoliata is an exception, valued for its deciduous nature and exceptional cold hardiness, making it important for breeding and as a rootstock in colder citrus-growing regions.

Answer 1

The Correct Option is A

The question seeks a citrus relative that is both deciduous (loses its leaves in winter) and extremely freeze-hardy (can withstand very low temperatures).
(1) Poncirus: This refers to Poncirus trifoliata (Trifoliate Orange or Hardy Orange). It is distinct among citrus and its relatives because it is deciduous and highly cold-hardy, tolerating temperatures well below freezing (e.g., down to -20°C to -26°C). It's often used as a rootstock to confer cold hardiness to other citrus varieties.
(2) Eremocitrus (Australian Desert Lime): These are evergreen and drought-hardy, with some frost tolerance, but not as extremely freeze-hardy as Poncirus, nor are they deciduous.
(3) Microcitrus (Australian Finger Limes, etc.): These are generally evergreen and vary in cold tolerance but are not deciduous or as freeze-hardy as Poncirus.
(4) Clymenia: A rare citrus relative, evergreen, and not known for extreme freeze hardiness or being deciduous. Therefore, Poncirus trifoliata is the correct answer as it uniquely fits both criteria of being deciduous and extremely freeze-hardy. Poncirus