Flora Picture of the Year 2013 : Vijayasankar Raman : 1 image. 18 posts by 14 authors.
Here is my ‘Flora Picture of 2013’! Although this is not colorful, it is one of my favorite SEM shots.

Calcium oxalate crystals are present in almost all kinds of tissues in more than 75% of the flowering plant families. They are also found in other plant groups. This raphide crystal is one of the commonly occurring five main types of calcium oxalate crystals.

The young raphide bundle in the attached picture (magnified 800x) contains about 200 needles kept together by thick mucilage.

Raphide crystals play multiple roles in plants including protection from herbivory, calcium regulation, removal of toxic oxalate etc. etc. Since the type and distribution of these crystals in plants are tissue specific and species-specific, they are helpful in plant identification and taxonomy.

Have you experienced the painful itchiness in mouth after consuming certain types of tubers/corms (such as Amorphophallus and Colocasia)? That is due to these sharply pointed raphide crystals that poke, prick and hurt the soft tissues in the mouth and tongue. There are millions of such bundles of raphides in those corms. The needles are variously shaped and sharply pointed at both the ends/tips and can be up to 0.2 mm long.

The crystals dissolve in acidic (low pH levels) medium, hence we cook the tubers/corms in sour-tasting fluid (such as tamarind juice) to kill the crystals and also to make the food tastier 🙂

Thanks, … You always come up with brilliant side of Plant science.
Details are very layman friendly & easily understood.

Very novel picture … would have said “out of the world” but it seems to be “the world” in context of plants !

Astnoshing details, seems like an entire world lives inside, there are certain structures specially noticeable, they appear like fruting bodies of fungi, marvellous indeed…
Many thanks …

Thanks … for bringing out the beauty of inside of plant.

SEM pictures present a plant word unseen by naked eyes, thus revealing interesting information. Here these crystals are similar to ‘needle ice’ formed during early or late season in alpine zones. Calcium oxalate deposition is a characteristic feature of a section of Saxifraga genus known as ‘Kabschia section’ which have leaves with 1-many lime secreting glands often referred as lime pits or simply pits on adaxial surface.

I wish I could see the structure and secretion of calcium oxalate in Saxifraga species.
Beautiful picture and great expertise mastered here.

Thank you so much …, for your nice words. …, we have few species of Saxifraga in our repository. When possible I will try to see if I can find the lime pits in any of those species, and share the SEM pictures to you.

Thanks a lot … for makes me surprised with unparalleled photograph like your last year’s picture! The content of the write-up is also very interesting

Nice to see you active on efloraofindia. And what a wonderful pic!

Thank you Sir for the appreciative comments. I am thrilled and extremely happy to see you active on eFI, too. Thank you 🙂

Very beautiful & informative. Sir may I know the name of the plant and the plant part the SEM shot belong ?

Beautifully captured details not seen by our eyes.
Lovely picture!

Thanks … for the appreciations and comments.

…, the picture is of a Dioscorea tuber (cross sectional view). 

Can you please help me for the use of SEM Technique for the plant surface observation. I am looking for the basic principle, procedure for the plant surfaces.
i am trying for studying the pollution effect, thier interaction on plant surfaces.

I was able to get pictures of the lime pits and their calcium oxalate secretions in Saxifraga that you wanted to see. I am sharing the pictures in a separate thread…