No. 69 — Ternary citrus ⫶ Warm-blooded plants ⫶ Ruby’s Exceptional Creatures

Citrus does not come true from seed.

My name is Linda. I write a bi-weekly newsletter about computer science, childhood, and culture.

Physicist Freeman Dyson once gave a unique answer on raising world-class, imaginative physicists. He proposed to advocate for children to play with plants genetically.

Dyson further elaborated on the necessity of such creativity, especially if we aspire to one day colonize space. "Most of the surface area of the solar system is in the asteroid belt -- but the only way we could really live out there was if we could create warm-blooded plants," he continued.

I loved this answer.

It's surprising and stands out for its clarity, scope, and curiosity, even if space colonization isn't something I'm that interested in. I hope to see answers like these for broad and bland, all-encompassing questions like how to raise resilient and creative children with future-proof skills.

Play with plants! So good.

So it is with the spirit of Freeman Dyson I went to buy some citrus fruit. I've been reading John McPhee's Oranges, an irresistible book from the 1970s that traces stories around orange growers, barons, and pomologists. Coming from an apple country like Finland (a division introduced by one of McPhee's interviewees), there was so much new knowledge about how citrus is bred. Grafting a citrus tree felt almost as alien as Dyson's warm-blooded plants.

First:

"Citrus does not come true from seed."

What this means: "If you plant an orange seed, a grapefruit might come up. If you plant a seed of that grapefruit, you might get a bitter lemon." McPhee explains further how different rootstock traveled the ancient world, how grafting works, and how the oranges' soil, sun, and position in the tree influence the taste almost as much as wine.

Second:

"It turns out there are three basic ancient eigenfruits: true mandarins, pomelos, and citrons. And all the other fruits are various combinations of that triplet."

This ternary plot introduced by Matt Webb explains the relationships between different forms of citrus. It creates many questions - like what are the empty spaces, how did so many mandarins come to be, what is the difference between a lemon and a citron, and why haven't I paid any attention to pomelos?

Play with plants!

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Linked List

In computer science, a linked list is a linear collection of data elements whose order is not given by their physical placement in memory. But here it is a selection of things I’ve been reading lately.

• Freeman Dyson - Noah’s Ark Eggs and Warm-Blooded Plants. A video of Dyson talking about human exploration of the cosmos. I’m usually not interested in the space colonization tech talk, but this is lovely.

• Diagram.website. Kristoffer’s map of intriguing subsets of the Internet. Trying to locate myself on the map, I wander around ecology, fun and small.

• Ruby’s Exceptional Creatures. I love this bestiary of the most common errors in Ruby language! Meet SyntaxError, Net::ReadTimeout, and EOFError (and Honeybadger, their mortal enemy - and the company behind the guide).

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Classroom

I’m hoping to surface and share stories from all of you and I’d love to see your creations! Here are a few teachers using Ruby in creative, fun and inspiring ways.

Mrs Hannon’s students practice conditionals with different clothes. If it rains, wear boots and a raincoat - else wear a dress and sneakers! There’s also an activity to go with this with a paper doll - it’s called dress code, and you can find it here. 

An excellent, short interview I did a while back with Equitat Digital. The Catalan Ruby book is almost out of print, but a few are still on Amazon. 

South Sanpete School District in Manti, Utah, made a lovely companion guide for Hello Ruby: Journey Inside the Computer. If you’re teaching with this book, check it out!