Thanks to Jackie Chambers for another of her "global gardens" images (and accompanying write-up). Jackie writes:
Citrus medica var. sarcodactylis, or Buddha's hand, is an unusual member of the citrus family. The varietal name sarcodactylis is from the Greek sarkos meaning "fleshy" and dactylos meaning "finger". These graceful, fleshy fingers appear to gesture and invite you in for a closer look at this curious fruit.
The finger citron, as it is also sometimes called, has fruit that can range from 10-25cm long. The fruit starts out green, then turns yellowish-orange when ripe. It is composed of 5-20 finger-like segments, and the arrangement of these segments can vary -- the "fingers" can be held in a closed position like the one pictured above, or the segments can be more widely spread apart.
The technical term for a citrus fruit like this one is a hesperidium, which is defined as a modified berry with a tough rind. The external layer of rind is called flavedo, and contains pigments and pits with essential oils - contributing to the strong lemony scent of the rind. Read more about citrus fruit terminology via Wikipedia.
The interior of Citrus medica var. sarcodactylis is composed entirely of white pith or albedo -- there is no juicy pulp. The albedo is edible, and unlike other Citrus, this pith is not bitter to taste. This means the "fingers" may be eaten peel, pith and all. The strong scent of the rind makes it useful as a zest for flavoring and it is also candied (read some recipes and more related information).
Not only is the fruit used for eating, but in some parts of Asia, the rind is used in households as an air freshener because of its strong fragrance. The fruit is also used as offerings in religious ceremonies where the "closed hand" arrangement of segments is the preferred offering, as it said to more closely resemble a hand held in prayer.
Citrus medica var. sarcodactylis is a small tree or shrub, between 2-5 m in height, and, like many citrus, it has spines in the leaf axis. The leaves are oval in shape and 10-15 cm long. The flowers, ranging from white to pinkish purple, are held in fragrant clusters. For more photographs of the plant and fruit, see University of California Riverside's Citrus Variety Collection page on Citrus medica var. sarcodactylis.
Citrus species have been in cultivation for thousands of years which makes exact origins difficult to define. It is suggest they were initially understorey trees in the forests of southeast Asia and that Citrus medica var. sarcodactylis, in particular, may have originated in northwestern India.
Botany / photography resource link (thanks again to Hannah Bottomley, who contributed the BPotD on infrared-emitting conifers); Hannah writes: I interviewed a professor when I was in France who was in charge of digitizing the incredible lifework of an avid pharmacist/botanist. It is a very extensive herbarium, with plant specimens collected over the span of over 40 years (1861-1907), and is still the main reference for botanists in that region today. The quality of the images are amazing, and there is a zoom tool which allows you to see the plants in remarkable detail. He showed me the whole process of creating this digital collection -- he has accomplished truly amazing work.
If you would like to check out this herbarium, the link is here: Herbier Tourlet. To go through an alphabetical index of plants, click on Listes des plantes. Or if have a specific plant in mind, click on Recherche de plantes and type in the Latin name. Once you do, you'll see a large image on the right - notice the zoom to the bottom left of this larger image -- when you click on zoom, a new window will pop up, and you can keep clicking on the image to zoom in further and further. I also love that there is a red navigation box to orient you as to where you are! The small images on the bottom left are all the other specimens that were collected of that particular species.