Binomial: Zizia aurea (ZIZ-ee-uh / AWR-ee-uh)
Family: Apiaceae (ay-pee-AY-see-ee), the Carrot Family
We're so lucky to have Golden Alexanders living in St. Louis. When in flower, this cheerful plant is like a Ted Drewes frozen custard stand on a sweltering Tuesday evening after a Little League game. It's full of little tongues licking their sweet treats, especially the short-tongued bees, flies, beetles and wasps.
Golden Alexanders is from the Apiaceae, the carrot family. To be able to identify plants from this family, we need to know what an "umbel" is. The umbel is the #1 defining characteristic of this family. In fact the family used to be called the Umbelliferae. An umbel is an umbrella-like cluster of flowers (inflorescence) in which all the flower stems (pedicels) are nearly the same length and emanate from the same point. The flowers form a flat or slightly convex disk. But don't touch that dial, because there's more! Golden Alexanders and the Apiaceae don't just have umbels, they have compound umbels - "umbels of umbels"!
It's like a 4th-of-July fireworks display under the Arch. A mortar shell is shot up from a barge on the Mississippi River. When it gets up high enough, it explodes and creates a beautiful dome of sparkling shells. But then each of those secondary shells explodes to create the many-domed spectacle that people are still talking about days later.
Here comes a math problem. If the top of a Zizia peduncle (the stem that holds up the inflorescence) explodes into an umbrella of 12 rays, and if the top of each ray then explodes into an umbrella of 21 pedicels (each with a floret on top), how many florets might a single Zizia umbel contain? That's why the Golden Alexander in bloom is such a spectacle. And that's just one umbel! Each plant can have lots of umbels - thousands of ice cream cones!
Not all frozen custard stands in St. Louis are Ted Drewes. And not all yellow, double-umbellates in St. Louis are Golden Alexanders. The different species can be tricky to tell apart. Here is a list of Golden Alexander and her 6 St. Louis lookalikes that will challenge our powers of observation. Click on any of their names to see their photos (mostly from MissouriPlants.com):
Zizia aurea (Golden Alexanders) - the basal leaves are trifoliate compound; leaflets are toothed; central floret of each umbellet is sessile; fruits ridged but not winged; inflorescence emits strong musty odor;
Pastinaca sativa (Wild Parsnip) - taller, blooms later, compound leaves are single-pinnate rather than double-pinnate; has flat-topped umbels; leaflets have more than 8 teeth on each side;
Polytaenia nuttallii (Prairie Parsley) simple pinnate leaves; mature seeds have winged margin;
Taenidia integerrima (Yellow Pimpernel) - the oblong leaflets are toothless (entire); compound umbels open and airy; umbellets point in all directions like fireworks;
Thaspium barbinode (Hairyjoint Meadowparsnip) - central floret has pedicel; inflorescence emits strong musty odor;
Thaspium trifoliatum var. flavum (Meadowparsnip) - the central floret of each umbellet has a pedicel; the basal leaves are simple (not trifoliate);
Zizia aptera (Heartleaf Golden Alexanders) - has simple (as opposed to compound) basal leaves;
For more information on the Golden Alexander, please click on IllinoisWildflowers.info for their always thorough description.
For those of us trying to better learn our different flower types, Zizia aurea can help:
STANDARDIZED FLOWER COMPARISON FORM: (please click for GLOSSARY)
INFLORESCENCE: Zizia's inflorescence is a flat-topped compound umbel containing up to 250 florets. (An identifying characteristic of Zizia is that the central floret of each small umbellet is sessile - it has no obvious pedicel).
CALYX: Each little floret has 5 yellow sepals, fused to each other.
COROLLA: Each little floret has 5 yellow petals that curve inward.
ANDROECIUM: Each little floret has 5 stamens, lined-up with the sepals.
GYNOECIUM: Each little floret has an inferior ovary composed of 2 fused carpels with 2 styles.
FRUIT: The ovary from each little floret will mature into a small, oblong, 2-sectioned, ridged schizocarp which splits into 2 seeds.
- Michael Laschober
Week #6 (April 24-30) Golden Alexanders (Zizia aurea)
Please protect the plants in our natural areas:
Locations: [CUIV, DONR, HAWN, LITL, MERA, ONON, SHAW, STFR, VALV, WASH, YUNG]
Please click on the button below to see a list of the Apiaceae plants we're likely to find in St. Louis.