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2 Unusual Australian Citrus Species At Palomar College
© W.P. Armstrong 21 December 2021

       Buddha's Hand       Finger Lime  

  The Unusual Fruits Ripen During The Holiday Season In December  
When most people think of fruits in the genus Citrus (family Rutaceae) called hesperidiums, they think of globose, juicy fruits like oranges, tangerines & grapefruits depicted in following image. This page is dedicated to 2 strange citrus fruits from the Far East & tropical Australia.

Citrus fruits with familiar shapes and sizes, including grapefruit, lemon, lime, orange, pomelo & tangelo. The 2 Citrus species discussed on this page have very unfamiliar shapes. They are on the botanical garden campus of Palomar College.

Buddha's Hand or Fingered Citron (Citrus medica var. sarcodactylis)

Buddha's hand tree at Palomar College (22 Dec. 2021).

Citrus medica var. sarcodactylis is an unusual shaped citron variety whose fruit is segmented into finger-like sections. Buddha's Hand ripens in the winter months. When it first comes into season, the hand is closed, and the fingers look like the tentacles of an anemone. As the fruit matures, the hand spirals out like an octopus. The following is from Wikipedia (accessed 9 Jan. 2020): "The different cultivars and variations of this citron variety form a gradient from "open-hand" types with outward-splayed segments to "closed-hand" types, in which the fingers are kept together. There are also half-fingered fruits, in which the basal side is united and the apical side fingered. The origin of this kind of citron is commonly traced back to the Far East, probably northeastern India or China, where most domesticated citrus fruits originate. The fruit has long been prized in East Asia because it symbolizes happiness and longevity, and it's often given as an offering in temples and served during Lunar New Year."

Buddha's hand fruit is very fragrant and is used predominantly in China, Malaysia and Japan for perfuming rooms and personal items such as clothing. Unlike other citrus fruits, most varieties of the Buddha's hand fruit contain no pulp or juice. Though esteemed chiefly for its "exquisite form and aroma", the Buddha’s hand fruit can also be eaten (often as a zest or flavouring) in desserts, savory dishes and alcoholic beverages (such as vodka) or candied as a sweet. The sliced, dried peel of immature fruits is also prescribed as a tonic in traditional medicine.

Longitudinal section of Buddha's hand fruit.

Magnified longitudinal view of the endocarp of an orange (Citrus sinensis) showing several sections (carpels) filled with numerous fluid-filled "juice sacs." The two lower sections each contain a seed which is surrounded by the fleshy sacs. The sacs (vesicles) are actually swollen (plump), specialized hairs. According to K. Esau (Anatomy of Seed Plants, 1960), the juice sacs originate as multicellular hairs in which the interior of the enlarged distal part breaks down and fills with liquid. The juice sacs constitute the fleshy, edible pulp of an orange and are the source of the sweet juice. A bitter compound called limonin occurs in the mesocarp (rind) and membranous layers (partitions) surrounding the seed-bearing sections of grapefruits and other members of the citrus family (Rutaceae). The following article contains a more detailed explanation for the origin of juice sacs.

    Tisserat, Brent; Daniel Jones; & Paul D. Galletta (March 1990). "Juice Vesicle Populations in Citrus Fruit". Botanical Gazette. 151 (1): 9. doi:10.1086/337806.

Finger Lime (Citrus australasica)

  Again, Much Of The Information About Finger Lime Is From Wikipedia  

Although it is beyond the scope of this article, thorns & spines are quite different. They are both sharp, but have very different origins. Technically speaking, spines are modified leaves while thorns are modified stems. For anyone seeking more information on this fascinating subject, please click on the following link.

  Wayne's Word Page On Spines vs. Thorns  

Citrus australasica, the Australian finger lime or caviar lime, is a thorny understory shrub or small tree of lowland subtropical rainforest and rainforest in the coastal border region of Queensland and New South Wales, Australia. It has edible fruits which are under development as a commercial crop. It has been grown on a commercial basis in Australia in response to high demand for the fruit. Commercial use of finger lime fruit started in the mid-1990s with boutique marmalades made from wild harvested fruit. By 2000 the finger lime was being sold in restaurants, and exported fresh. There is an increasing range of genetic selections which are budded onto citrus rootstock. With the sudden high market demand for the fruit, the primary source of genetic material for propagation has been selections from wild stock.

The globular juice vesicles (also known as pearls) have been compared with a "lime caviar", which can be used as a garnish or added to various recipes. The fresh vesicles have the effect of a burst of effervescent tangy flavor as they are chewed. The fruit juice is acidic and similar to that of a lime. Marmalade and pickles are also made from finger lime. Finger lime peel can be dried and used as a flavoring spice

Magnified image of juice vesicle (juice sac) taken through compound microscope with back-lighting (40x). The fluid-filled vesicle is a swollen multicellular structure with a hairlike stalk. The following is from Katherine Esau (1962) Anatomy of Seed Plants: "The juice sacs are comparable to multicellular hairs but originate subepidermally, with the epidermis forming a single layer. The distal part of each hair is enlarged, and the interior broken down and filled with juice."

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