Speedwells are Back! Distinguishing Bird's-eye Speedwell and Grey Field-speedwell (Veronica persica vs Veronica polita)

Winter is just about here, which means cooler, wetter weather... and the speedwells are along for the ride.

I've seen 6 species of Veronica around Austin, and while all but one (Veronica peregrina, the purslane speedwell) are non-native, the other species are thankfully not invasive and largely restricted to disturbed sites. Their petite little flowers bloom even through the cold of winter, quickly bouncing back even after ice and frost. It seems their flowering season (in Texas at least) starts in late fall, around November or December, increasing their flowering output through January and February and into the peak of spring, before fading with the heat of summer. While others may regard them as little more than lawn weeds, their microblooms bring a little joy to my heart, a much-needed morale-boost for the overwintering botanist.

Most commonly seen is the Bird's-eye speedwell (Veronica persica), which I suppose given enough imagination could appear like a bird's eye. It can however be easily confused with a very similar-looking species that is much less observed in Texas, the Grey field-speedwell (Veronica polita).

Case-in-point: As of me writing this post there are just over 3,000 observations of Bird's-eye speedwell. Meanwhile, there are just over 600 observations of Grey field-speedwell. That's five-times less than the former species.

We are fortunate to have the taxonomic authority on speedwells on iNaturalist, Prof. Dirk C. Albach, who authored the Flora of North America treatments for the genus. I humbly owe most (if not all) of my information on distinguishing these species from him. Drawing from comments he has made on previous observations, you can reliably distinguish the two species... if you know what to look for.

Field Identification Notes between Bird's-eye Speedwell (Veronica persica) and Grey Field-speedwell (Veronica polita)

Photos for best shot of ID

• Front photo of flower.
• Back photo of flower to see the sepals
• Photos of the fruit

The other two are not as easy to capture but I give details and advice on photographing them in later sections.

Example observations:
https://www.inaturalist.org/observations/196550220) for an ideal example
https://www.inaturalist.org/observations/109845925 with less "fancy" photos, but just as IDable as the first

Corolla lobe/petal overlap

The four petals of Bird's-eye speedwell tend to overlap, particularly the two lateral petals with the posterior petals (left image). Those of Grey field-speedwell don't tend to overlap, often to the point where there can be a narrow gap between the petals (right image).

In both images, the flowers are right-side up. The top petal is the anterior petal, the paler bottom one the posterior petal, and the two middle petals on the left and right side are the lateral petals. In general it seems the anterior petal is most strongly pigmented blue, while the posterior petal is the palest, which helps with determining which is which. Note also the the posterior petal is often noticeably less wide than the other 3 petals.

Sepal width relative to the petals

Grey field-speedwell has broad, ovate sepals, which are about as wide as the petals. Those of Bird's-eye speedwell are narrowly elliptical, particularly when compared to the petals.

The sepal width difference trait can be used on very young fruit, where the flowers have fallen away and the fruit is just starting to develop (and young fruit are often unintentionally captured in the background of photos). On more mature fruits, the persistent sepals appear to enlarge and it becomes difficult to tell. The easiest way to see the difference, in my opinion, is to flip the flower over and get the backside:

Left is Bird's-eye speedwell, right is Grey field-speedwell. You can see quite clearly that the petal on Bird's-eye speedwell is much broader than the sepal underneath. Note how on the Bird's-eye speedwell, you can easily fit the sepal inside the lateral petal—it's that much smaller. Meanwhile on the Grey field-speedwell, the sepals could easily cover most, if not all, of the petals, if aligned right.

Generally this is most obvious in comparison with the lateral and anterior petals, since the posterior petal is often reduced and so often closer in width to the sepals.

This characteristic is the most obvious to me and seems fairly easy to capture; either bend the flower so that the back is visible, or pluck one off altogether and plant it face-down for photographing. Sometimes it helps to pluck off the top set of leaves near the flowers if they obscure the sepals when bending the flower over.

Another sepal characteristic that has been used the relative length of the sepals compared to the flowers. In Grey field-speedwell, the sepals are often long enough that they poke out prominently from behind the petals; in Bird's-eye speedwell, the sepals are less long relative to the petals and only the apices of the sepals stick out from behind the petals. This seems to work fairly well in cases when the sepals are mostly hidden behind the petals (in which case those are very likely Bird's-eye speedwell), but occasionally you may find a Bird's-eye speedwell with the sepals showing-off more and extending beyond the petals like Grey field-speedwell, which adds some ambiguity. Thus, I prefer relying on sepal width relative to the petals.

Fruit shape

Getting updated...

The shape of the fruits are noticeably different between these two species.

For both species, the fruit has two lobes with a indent in the middle, the sinus. The fruit for Birds'-eye speedwell (at left) has lobes that are divergent from each other, with a wide sinus angle. The fruit for Grey field-speedwell (at right) has lobes that appear tighter, with a smaller, narrower sinus.

Bird's-eye speedwell is on the left and Grey field-speedwell is on the right.

If you've found a speedwell in bloom, it's likely that they have fruit on them! Look for older plants, then follow down the stems away from where the flowers are.

Speedwell stems with fruit on them. Notice how they get larger and more mature as they go down the stem.

The characteristic used in Flora of North America to distinguish the two species is through the fruit as well, although not as clear to the eye. The fruiting capsules of Veronica have two main lobes, and in-between the lobes is a little indent or "sinus." For Bird's-eye speedwell the sinus is deep, with a typical sinus angle ranging from 90–120 degrees. The sinus in Grey-field speedwell is shallow with an typical sinus angle ranging of 20–60 degrees.

Grey field-speedwell seems to be under-documented in Texas, probably because of its close similarity to the more commonly-observed Bird's-eye speedwell, and perhaps its smaller corolla size. I hope this post clears up any confusion regarding the two species, help observers better document the less common of the two, and perhaps bring a little more attention to these petite microflowers as they say, "wait a little, wait a little longer—spring will be coming."

Observations referenced:
https://www.inaturalist.org/observations/39519276
https://www.inaturalist.org/observations/71076202

Publicado el diciembre 17, 2023 12:47 MAÑANA por arnanthescout