Anatomy of an apple - A Short Study

The apple is just one member of the massive Rosaceae family that contains over 2800 species located in 95 genera. Lots of these species are useful as food products and the apple must be among the most popular of these. The apple is also classified in a subtribe called Malinae. This subtribe contains around 1100 species in 28 genera, including hawthorn and cotoneaster. The fruits of Malinae are accessory fruits called pomes, which is derived from pōmum, which is latin for fruit.

Folklore
As the saying goes "An apple a day keeps the doctor away", but where does this saying come from and what does it mean?
The earliest variant of the saying comes from a 1866 edition of the Notes and Queries magazine which states: "A Pembrokeshire proverb. Eat an apple on going to bed, And you'll keep the doctor from earning his bread." It's worth knowing that in Old English the word apple (æppel) could mean any type of fruit or just fruit in general.
However, we now know that it's not just a nifty saying. The apple contains many chemicals that are useful for us from vitamin C to a range of phytonutrients (substances found in plants that have nutritional value) that can mop up free radicals. Apples have also been used as a 'poster boy' recently to point out that everything is made of chemicals and that not everything man-made is terrible for us - click here to view.

The apple is abundant in our history; from apples bobbing being a traditional halloween activity to the cockney rhyming slang for stars (apples and pears). While never specified as an apple, most people associate the apple with the forbidden fruit of Genesis that Adam and Eve ate - however this may be due to the painters of the Renaissance needing some sort of fruit to paint. It is suggested that the Renaissance painters entwined the greek mythology of the tree of life and its golden apples with the Genesis fruit from the tree of the knowledge of good and evil.

The apple occurs so much in our history and folklore, that books could be written about it! For more information, try an Internet search. For now, let's move on to the anatomy of the apple.

Flower of an apple tree

Anatomy
The anatomy of fruits is interesting and the apple is a helpful fruit in helping to understand it. If you eat multiple apples off the same tree, or if you buy a brand of apples (such as Granny Smith apples which reputedly germinated from an Australian woman's compost heap); you know that the apples from a single tree/cultivar taste the same. 

This is because apples require cross-pollination, so the seeds of each apple may have been from pollen of many different trees (anthropomorphically speaking: from many fathers), all the apples from a single tree only have one mother. So, as the part of the apple we eat is developed only from the mother (1n), all the apples on a single tree will taste the same. As seeds are from both parents (2n), growing an apple tree from seed will lead to apples that taste different from both parents - sometimes this will lead to a tasty new variety; but often this is not the case.

An apple is known as an accessory fruit, meaning that not all of the fruit is from the ovary. In the case of apples (and pears), the fruit flesh is from the hypanthium. The hypanthuim is also known as the floral cup and is the base of the perianth (outer part of the flower) which connects the sepals, petals, and stamens. As you can see in the photo below, the hypanthium enlarges greatly after fertilisation and becomes the fleshy (and rather tasty) part of the apple. The pedicel is the stalk at the top of the apple, which originally held the flower and goes on to hold the fruit as it hangs from the tree.

The semi-circle mark on the left of the apple was left by something that got to the apple before me!

The flowers of the Rosaceae family often work in multiples of 5. In the flower photo above, you can see 5 petals and 5 anthers. In the fruit photo above you can see the marks of 10 stamen (apologies the the cut mark and the bug hole hiding 2 of them!) as well as 5 ovary chambers. 

So, the next time you eat an apple, be thankful for the enlarged hypanthium that is enriched with many phytonutrients that will keep you healthy and taste great!

References

Mabey, Richard. Flora Britannica. 1st edition. London: Chatto & Windus / Sinclair Stevenson, 1996.

Allaby, Michael. A Dictionary of Plant Sciences. 3 edition. Oxford: OUP Oxford, 2012.

Apple Anatomy Cross-Section. 2014. Apple Anatomy Cross-Section. [ONLINE] Available at: http://appleparermuseum.com/AppleAnatomyCrossSection.htm. [Accessed 18 August 2014].