Life on the Outer Coast

DYCs!

Because there aren’t really that many native yellow composites in SEAK, I don’t often have to use DYC too often anymore. Then one day, I decided it was time to get better acquainted with the weedy species around town.

The two plants that caught my attention were growing in the gravel at the edge of the road to the work float near the island side of the O’Connell Bridge. The yellow ray flowers, milky juice and clasping leaf bases made the genus identification fairly straight forward for both plants; Sonchus or Sow thistle. I wasn’t so sure about the species identification of either plant.

At this point, I should confess that I tend to use keys to identify plants, then look at the descriptions and photos/drawings, so the following paragraphs mostly talk about comparing the keys in various books.

I first consulted Invasive Plants of Alaska which includes a description of perennial sow thistle (S. arvensis ssp. uliginosus) and a paragraph about differentiating one species of annual Sonchus (oleraceus) from the perennial one. This text focused on the long horizontal root systems found in the perennials. There was a photo of the leaf base of the perennial (rounded) and the annual (had longish pointy auricles).

Neither plant had a well developed root system, but they might not if they were first year plants. So I looked for additional references.

To sum up this book focused on the root system and auricle shape. S. arvenis has a large root system and rounded auricles.

The key in Hitchcock and Cronquist also referred to differences in the root systems, but added size of flower heads; perennial are 3-5cm and annuals species 1.5-2.5 cm. Lastly, H & C included gland tipped hairs as a characteristic of S. arvensis (this character turned out to be a bit of a red herring). One of the plants had this character, so despite the flowers being a bit on the small size, I was pretty certain that one of the species was arvensis.

To sum up H& C use root system, flower head size with a mention of glandular hairs.

Because the line drawings didn’t really fit what I had in hand, I decided to consult another reference. FNA treatment

This key begins with leaf base auricle shape, number of ribs on the cypsela (fruits) and introduces the idea that one of the species treated as an annual in the last two references, could be a biennial.

Second decision in this key involved life history as well as stem hardness (…”stem bases soft to hard, herbaceous, often hollow” vs. “stem bases hard, sometimes more or less woody”. I think I’ll emphasize the woodiness issue.

Once a direction is chosen, the leaf blade shape is important in differentiating S. oleraceus from S. ternerrimus (leaf blades more or less deltate to lanceolate with the terminal lobe larger vs rhombic to lanceolate and equal sized.

Between arvensis and palustris; geography helps (Ontario vs. widespread) and the leaf base. S. arvensis is rounded and palustris acute auricles

To sum up the FNA (widespread spp only, this removes ternerrimus and palustris from consideration)

S. asper has recurved auricles and fruit with 3 ribs on each face annual or biennial

S. oleraceous: has straight auricles, and lobed leaves with a larger terminal segment and often hollow stems.

S. arvensis: straight auricles, hard stem base, rounded auricles and dark brown cypsela at maturity.

Although I already had a bit more information than I wanted, I decided to consult another favorite reference; Anderson’s Flora of Alaska

Although there was common ground between this and other treatments, another new character came into play; involucres bract length. Also, this key indicated that the annual species could have stipitate glands.

S. arvensis: perennial, involucre bracts more than 14mm long in fruit, pubescent with stipitate glands

S. asper:annual, involucres less than 14mm, leaves with sharp and narrow pointed teeth, cypsela not wrinkled, but longitudinally nerved

S. oleraceus: annual, involucres bracts less than 14mm, leaves sharply and broadly toothed, lyrate pinnatifid (handy character), cypselae transversely wrinkled and longitudinally nerved

I had one last reference at my disposal; the Illustrated Flora of British Columbia . Fortunately the descriptions fit in pretty well with those found in H &C and Anderson.

S. arvensis: perennial, heads 3-5cm

S. oleraceus: annual or biennial: flower heads 1.5-2.5, cypselae several nerved and wrinkled

S. asper: annual or biennial, flower heads 1.5-2.5 cm, cypselae several ribbed, not wrinkled.

The handy thing about these taxa is that there doesn’t seem to be any noticeable disagreement in the taxonomy, just a bit of variation on which characters might be useful and a bit of haziness about how variable the presence/absence of certain character (glandular hairs).

So the synopsis of all keys

S. arvensis: perennial, straight auricles with rounded bases, may have woody stems, they may also be hollow, heads 3-5cm stipitate hairs present on the flower stems, and dark brown cypselae at maturity

S. asper: annual or biennial, stems not woody, may be hollow, leaves with sharp and narrow pointed teeth recurved auricles. Flower heads 1.5-2.5 cm and involucres bracts less than 14mm, fruit with 3 ribs on each face, not wrinkled

S. oleraceous:, annual or biennial, stems not woody, may be hollow. Leaves sharply and broadly toothed, lyrate pinnatifid, auricles straight, cypselae transversely wrinkled and longitudinally nerved

At this point, I’ve decided that for unambiguous identification (at least the first time around) I need mature seeds.

Back to the actual plants in hand; both have flowers less than 3cm (but neither are really fully open). Neither root system is obviously forming horizontal branches. The fruit aren’t fully mature, I can see ribs, but it isn’t clear if they are or will be wrinkled

One has rounded auricles, some stipitate hairs and very pointy large teeth on the leaf margins, the leaves are also darker and thicker. (I’m going with S. asper)

The second has straightish auricles with pointed bases, no hairs and less menacing teeth, the leaves are lyrate pinnatifid (like a dandelion) with a larger terminal segment. (going with S. oleraceus)