Paying attention to the tiny details of the world is one of the sweetest pieces of being a part of it. This practice — which I think is definitely a learned skill, especially in our attention-deficit disordered culture — has helped get me through some very rough times (along, of course, with coffee, beer, and music). This petite mindfulness is as essential to the naturalist as is the bigger, broader picture of life-sustaining cycles and ecological relationships, two sides of the same blue-green coin.
Here are three plants that, whenever I encounter them, I’m compelled to check out their leaves even though I’ve already done so countless times previous. Though I’m no longer surprised by what I find on the underside, I’m also stoked by it. It’s sort of like greeting a friend with a kiss on the cheek even if you see her everyday.
=the indigenous name) was the very first species I learned in my two semesters of Plant I.D., and as such hold it near and dear to my heart, even though I had never noticed this small tree previously. Its scientific name literally means “many golden pores.” Hold it up to the sunlight, and its nomenclature becomes immediately apparent — hundreds of yellow pinpricks polka-dot the surface of the otherwise typical leaf, illuminating it like a cityscape in the night sky. These golden pores are actually structures called “pellucid glands,” which are a type of oil-containing cavity that are common in citrus (you know this, peel an orange). In myoporum, this essential oil makes the leaves incredibly toxic.
This didn’t stop the city of San Francisco from planting this New Zealand native along the western edge of Golden Gate Park and liberally along city sidewalks in the ’60s and ’70s. But it is now a relic outlaw, as its invasive, concrete-rupturing roots and wacky growth pattern have caused its planting as a street tree to be prohibited. Myoporum’s round, magenta berries are spread by birds, and it is considered an unwanted invasive from Sonoma to San Diego. While you’re checking out those golden pores, look for the small white flowers, too, dotted with purple flecks and tiny white hairs.
Coprosma repens (TAUPATA) is another New Zealand plant common along the San Fran streets (similar mild climate = similar plants — plus both are resistant to salt spray). And it’s another one of those species, like Myoporum, I once shunned for its vulgarity — its thick, shiny leaves, its lack of defining style, its tacky ubiquity. Its common name, “mirror plant” or “mirror shrub,” gives away the highly reflective quality of its leaves, reminiscent of greasy teenage skin or a creepy sweaty dude.
However, I did a 180 on my snotty plant-itude and became a Coprosma convert when I learned that underneath this shiny surface there are visible stomata lining the midrib (the center leaf vein). Since hearing this, I’ve checked dozens of mirror plant leaves, just to make sure, and I find it absurdly reassuring — amidst a world filled with war, climate change, and shitty albums you’ve been waiting to hear for two years — that they are indeed always there (does this betray that I’m a huge dork? Yes.). See?:
Though you can’t see the two guard cells flanking the stoma (Greek for “mouth”), which open and close to allow carbon dioxide, oxygen, and water vapor to move in and out of the leaf (and in turn, the entire plant), on most plants they’re totally invisible to the naked eye. Depending on the species and the growing conditions, there are 100-1000 stomata per square millimeter on the underside of a leaf. The fact you can see a few giant ones on Coprosma makes it an especially rad plant.
In addition to the common green shrub, there are lots of cultivars showing off sunset colors of golden, red, copper, pink, and cream — all still, of course, with the tiny holes on the underside (though you may want to check, indefinitely…..).
Thujopsis dolobrata (ASUNARO), a cypress native to Japan, has the most beautiful design of all three. “Dolobratus” means “shaped like a pickax,” and the scale-like leaves are reminiscent of butterflies, so I refer to them as “butterfly pickaxes,” though the tree is sometimes referred to as “Deerhorn Cedar,” which works too. Thujopsis is traditionally planted around Japanese temples (and can be found as a hedge in GG Park’s Japanese Tea Garden) — these photos were taken of one sort of sad-looking specimen at the Stanyan/Oak entrance to the Panhandle.
Turn over the dark green needles of a Thujopsis and you’ll find each of the small divets colored white, like someone painted them with Liquid Paper.
What’s up with this? The white undersides are known as “stomatal bands” (no, not “stoner metal bands,” although I might start calling them that). So many stomata are packed into the concave leaf-scale that the sun reflecting off all of them makes them appear white. This is common in conifers on the underside of their needles.
The point? Sometimes there’s more to a leaf than just what’s on the surface. It’s like a Hallmark card, or something your mom would tell you. Perhaps now you will become as neurotic a leaf-underside checker as I. Good luck with that.