Week Seven: Plant keys and Westcave Preserve

Retired biologist Chuck Sexton made a cheesy face when I snapped this photo. We have a lot of fun during our Thursday classes and field excursions.

With online databases and field guides with photos, nowadays it’s fairly simple and easy to identify plants, insects and other flora and fauna. But REAL biologists and other experts use a key to nail down the specific genus and species of a specimen.

Week Seven of our Texas Master Naturalist training with the Highland Lakes chapter introduced us to using a basic plant key. We met at the home of Mike and Sammy (our training program coordinators), where retired biologist Chuck Sexton spent the first half of our morning going over basic terminology.

“I started keying out plants in junior high,” said Sexton, who grew up in California and formerly worked with the Balcones Canyonlands National Wildlife Refuge. “Knowing the terminology is important when going through a plant key. You’ll spend a lot of time just learning that.”

“If you want to be absolutely right in identifying a plant, you’ve got to key it out,” Sexton added.

So what’s a plant key? According to Vascular Plant Systematics, “keys are devices consisting of a series of contrasting or contradictory statements or propositions requiring the identifier to make comparisons and decisions based on statements in the key as related to the material to be identified.”

In other words, you look at certain characteristics of a plant and, by a series of questions and deductions, you narrow down possibilities to a specific identification. Basic characteristics include:

·      Petiole (leafstalk)

·      Stipule (leaf-like appendage at base of leafstalk)

·      Stem arrangements

·      Margins (leaf edges)

·      Leaf arrangements

·      Leaf shapes

·      Vein arrangements

For an hour and a half, Sexton reviewed plant characteristics and defined leaf-shape terms used in keys like lanceolate (spear-shaped), oblanceolate (“ob” means opposite of), reniform (kidney shaped), cordate (heart shaped), falcate (curved) and deltoid (triangular). On our handouts, I penciled in definitions as we went. My goodness, there’s a lot to know and learn about a basic leaf! THEN consider how many species of plant leaves there are! Mind boggling!

After Sexton’s lecture, we headed to the front yard for our first exercise in plant keying. We used a two-page "Artificial Key to Some of the Woody Plants on Westcave Annex" (for practice in Master Naturalist classes).

Is this a vine? Tree or shrub? The first question is simple: We've got a tree. On our key, we jump from #1b to #3.

Are the leaves opposite? Or alternate? They're alternate. So from #3b, we jump to #8. Now are the leaves compound or are they simple? They're simple so we jump next to #14. Are the leaves in a basal rosette, not arranged along twigs? That's a twistleaf yucca, which this specimen clearly is not. Are the leaves alternate along obvious twigs? Yes. So we jump to #15. Now are the leaf blades linear (very narrow), more than 10 times long as wide? No (that's a Roosevelt weed). Or are the leaf blades oblong to ovate, much less than 10 times long as wide? Yes–so we jump from #15b to #16. Are the leaves deeply tooth or lobed, the lobes separated by sinuses almost as wide as the lobes? No (that's a Texas oak). Or are the leaves shallowly toothed, with no discernible lobes? Yes–from #16b we go to #17. Are the leaf margins entire (without teeth)? Yes (they're not toothed)–from #17a we go to #18. Are the leaves less than 2 inches long? No. Are they more than 2 inches long? Yes–we go from #18b to #20a. Are the leaves stiff or brittle, the upper surface dark glossy green, veins inconspicuous? No. Are the leaves flexible, the upper surface full green (not glossy), veins conspicuous? Yes–from #21b we go to #22. Is this a shrub? No. Is this a tree with leaves more than 1 inch long? Yes–we go to #23. Are the secondary veins unbranched and parallel? Yes to #23a!
We've got a cedar elm (Ulmus crassifolia)!

"Isn't that cool how that works?" exclaimed fellow trainee Kay.

What's this, Sexton asked, a vine or a shrub?

We keyed this specimen out to a Mustang grape vine (Vitis mustangensis).

Sexton pointed out a Virginia creeper.

He explained leaf arrangement of a honey mesquite (Prosopis glandulosa).

This katydid came with my specimen.

Coral honeysuckle with a perfoliate leaf base. Cool! We have this vine in our Wildscape...I've got to check this out. 

Pete helped key out this elbowbush (Forestiera pubescens). "This is so cool," said classmate Janis of our plant key exercises. "Yes, isn't this exciting?" nodded Betty, a Master Naturalist from our chapter. "You ALL get an A!" Sexton pronounced when our keying exercises ended.

Noon lunch break on the back patio.

Next we headed to Westcave Preserve, where we found this guy on my back windshield...a truncated true katydid (Paracyrtophyllus robustus).

John, our guide, tells us about the Environmental Learning Center at Westcave Preserve. 
Early settlers named the site “West Caves” because of its location west of the Pedernales. Until the late 1970s, trespassers heavily damaged fragile vegetation and cave formations at the collapsed limestone grotto. Since 1976, careful management and limited visitation has allowed the habitat to heal. Access to the 70-acre preserve is by guided tour only (Saturdays and Sundays, weather permitting, 10 a.m., noon, 2 p.m. and 4 p.m.).

John also shared about the area's geology.

A view of the Pedernales River and distant hills from an overlook at the preserve.

Heading down the half-mile trail.

I believe this was identified as a Texabama croton.

Along the way, we spotted a summer tanager high up in the trees (no photo).

A native passionflower vine.

Stopping to take photos.

This old cypress was....

...very very VERY tall!

Off the trail, someone spotted what was believed to be a copperhead. Which had apparently eaten recently. See the big bulge?

I got as close as I dared to get a better photo.

We've reached the bottom of the canyon, where we cross Heinz Branch.

The Grotto.

I couldn't resist photographing this delicate fern.

We hiked up inside the Grotto.

View looking out from the Grotto.

Some of us hiked up to the cave, too.

Old graffiti carved into the cave's limestone floor in 1883.

A red-eared slider didn't seem to mind our company.

Another passionflower vine.

Our snake friend was still around when we made our return trip back up the trail.

Blue curls

NEXT WEEK

Our class curriculum takes us right here to MY TOWN–Blanco–where we'll learn about more invasives and entomology at Blanco State Park (where I lived for 13 years).