Field of Science

How do you tell the difference between a palm and a cycad?

Their terrible attempts to answer this question indicate that my students really don't want to know the answer. This is one of those terrible defeating moments when you realize that your efforts to provide engaging activities, like comparing palms and cycads, were all for naught. Cycads are very palm like to the point that some are called palms, e.g., sago palm (Cycas revoluta). Cycad leaves have two rows of leaflets like that of many palms, and the leaves are borne in helical whorls at the ends of stems, and cycads often have a stocky main stem and little or no branching. However actually cycads are more fern like than palm like. The leaves develop by uncoiling like fern "fiddle heads" (left). Palm leaves encircle the stem so the trunks bear the familiar leaf scar rings. Cycad leaf scars are much smaller and helically arranged; no circles. Nobody, nobody responded correctly about cycad leaf development. Groan. This is why grading exams is such an awful thing to do. Sometimes you just want to rip off their heads and pour the botany in.

7 comments:

Anonymous said...

That's too bad your students didn't know the answer to the question. It's pretty simple, really, the way you explained it.

Wonder if it's your teaching style which is partly to blame, as you seemed exasperated with the students, and that probably comes across.

Make two students stand up, and have one be a cycad, and the other a palm. Arms are fronds/leaves. Have rest of students make cycad and palm act like they should... how tall, put some fruits/flowers on the palm, etc.

The Phytophactor said...

Yah. It's my teaching style. Too much science, not enough interpretive dance.

Anonymous said...

Having been a teacher for thirty five years, and having to undergo all the changes in child{adult}/relationships over those years, I had a great chortle after reading your last sentence. I have forgotten the number of times that I would have liked to do that.

Anonymous said...

I don't find the answer all that simple, although I am interested enough that I specifically googled this question-that's how I found this page. For example, does the second picture show a palm or a cycad? As I see it,the scars form neither a circle or a helix.

The Phytophactor said...

If you draw a line between successive leaf scars, the line forms a spiral. Palm leaves encircle the stem at their base and leave circular scars around the stem.

Anonymous said...

Thanks! Today I shaw the palms at the edge of the road and for the first time since I learned about cycads I was certain that they are palms.

Michael the Boombringer said...

No need for cycad dance, students don't learn because they don't want to.