Sunday, February 14, 2016

A Valentine's Day Species Spotlight!

Roses are Red
Violets are Blue
Sugar is Sweet
And so are you! 

A classic oldie, but goodie poem that makes the rounds on Valentine's Day. For this very special Species Spotlight we are going to take a quick look at the 3 plants that star in this classic nursery rhyme.

Roses
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are not always red! I briefly talked about roses at July 4 as they are the national flower of the USA. The Rosaceae family contains over 2500 species, including some agriculturally important ones: apples, strawberries, raspberries, pears, plums, and more. The poem above is, of course, talking about flowers from the genus Rosa. There are over 100 species in this genus.

And while "Every rose has its thorns" is a popular lyric, rose thorns are not true botanical thorns but rather prickles. Thorns are a modified branch. Prickles are modified from the epidermis tissue on the stem. Though I suppose "every rose has its prickles" does not sound as sharp ;)

Violets
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are not usually blue! The Violaceae family contains around 800 species, the commonly called violet flowers are within the genus Viola. Viola sororia or the common blue violet, is quite popular representing Illinois, Rhode Island, New Jersey, and Wisconsin as the state flower. Violets have 5 petals and 5 sepals (the green part behind the petals) that are arranged asymmetrically. Their leaves and petals can be heart shaped which makes them a nice match for Valentine's Day.

The bright coloration of violets is to attract pollinators, such as bees. The bees will have to burrow deep into the flower to get to the nectar, ensuring pollen will be transferred to the bee to be taken to another violet. Violets have fascinating seed pods that allow the seeds to become flying projectiles. Drying out of the seed pod increases the pressure and eventually POP! Seeds go flying. This allows the violet to spread rapidly. This rapid spreading, and hardiness of the seeds, contributes to the ability of violets to quickly spread over an area. Watch the video below to see the amazing exploding violet seed:


Another incredible way that violets can spread seed is via ants. Violet seeds are covered in a rich oily covering called an elaiosome. This sugary oil attracts the ants which drag the seed back to their nest. After the elaiosome is consumed, the exposed seed can now germinate in ant fertilized (read full of ant poop) soil. This mutulistic relationship has a very long fancy name: myrmecochory and it is found in 1000s of other flowering species.

Sugar Cane

is indeed sweet, after processing. Sugar cane is a grass from the genus Saccharum and it is in the same family as other important crops such as wheat and rice. Sugar cane is though to have been introduced to America by Christopher Columbus. The tall, thick stems of sugar cane have a sucrose filled sap. This sap is removed and then boiled and crystallized to form sugar! Since the stems, and not the fruit, are the agriculturally important part, they can be harvested repeatedly without having to replant from seed.

As a fan of photosynthesis, in my opinion one of the coolest things about sugarcane is how they do photosynthesis. They do what is known as C4 carbon fixation. Light capture happens the same way in C3 ("normal" photosynthesis) and C4 plants, it is the Calvin Cycle that is different. One of the downfalls to photosynthesis is photorespiration, when RuBisCo utilizes oxygen instead of carbon dioxide. To get around this, C4 plants have a special modification, called kranz anatomy.


Inside the leaf, there are "wreath" shaped bundles of bundle sheath cells surrounded by mesopyll. Only the bundle sheath cells have RuBisCo and all of the carbon dioxide produced by the light-reactions is passed to these bundle sheath cells from the mesophyll cells. The movement of carbon dioxide between the cells is facilitated by a 4 carbon compound, hence the name C4 carbon fixation. This is advantageous as it concentrates the carbon dioxide around RuBisCo and drastically reduces the amount of photorespiration. Reducing photorespiration means that more energy goes into sugar production. Thus C4 carbon fixation is the true reason sugar is so sweet.


And so are You

Happy Valentine's Day to all of my readers!

References

http://ipm.missouri.edu/meg/2013/1/of-thorns-spines-and-prickles/
http://pick4.pick.uga.edu/nh/tx/Plantae/Dicotyledoneae/Violaceae/Viola/
http://wp.stolaf.edu/naturallands/woodlands/ephemerals/commonviolet/ 
http://www.kew.org/science-conservation/plants-fungi/saccharum-officinarum-sugar-cane 
http://www.uic.edu/classes/bios/bios100/lectures/ps02.htm

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