The amazingly strong stem of the giant sunflower plant

Early Russian sunflower with about half the florets open. I'm always amazed to watch how they open in a constricting spiral from the outside, in.

I remember sitting in Biology class way back when and learning about the cross-section of the plant stem. Those black and white line drawings were, well, just lines on paper to me.

Now, however, after cutting down my spent Early Russian sunflower plant, I have a deeper appreciation for that particular lesson.

Not only was the flower head big and heavy, the plant itself was tall (over 2 metres high). The stem that held it all up was ramrod straight, and to do that, it had to be hard and tough. Regular hand-held cutters couldn’t sever the stem at the base. I had to use the heavy-duty shears that we normally use for woody branches – and although the sunflower stem was green in colour, cutting it sure felt like I was cutting through wood!

Looking at the cross-section of the stem, I was immediately reminded of those Biology lessons…

View of the cross-section the the Early Russian sunflower's tough stem.

…which I’m not going to attempt to give here, for a Biology teacher I am not. An inquisitive person, I guess I am. I was just intrigued by the spongy white pith in the middle that resembled spongy packing foam. Not only was it tough and expanded back to shape after being pressed, it was also very moist, like a sponge. Now I know how the plant transported nutrients…

Surrounding that were the tough and fibrous external layers – I guess that would be the xylem, phloem and epidermis. That layer was difficult to peel off. It was hard and had tough fibres embedded in it, reminding me of sugar cane. It was almost like a hard nutshell! When I tried to peel it off, it broke off with a cracking sound, and was difficult to strip away from the pith. Now I understand how the plant held itself upright so well…

After stripping off the outer layer, the spongy white pith is exposed.

Isn’t it so amazing how plants adapt to suit their needs?

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The amazingly strong stem of the giant sunflower plant — 4 Comments

  1. O no! Forewarned is Forearmed! I will be doing the same thing in a few weeks’ time. An interesting post!
    I cannot remember ANYTHING from Lower Sec Biology…

    • The smaller sunflower varieties are not as bad, NoviceG. At least mine weren’t. I could just pull lightly and uproot the spent plants. This giant baby was a totally different story. I’m waiting to see how long the little stump that keeps tripping me and the roots will take to decompose naturally.