Hyssop Spurge

Euphorbia hyssopifolia

Description 4

Plants robust, ascending to erect annuals; hairy or glabrous; may attain a height of over 30 cm tall; not typically branching much at the base. Stems glabrous (with scattered pilose hairs in other areas); largest internodes may get up to 3 mm in diameter. Stipules fused on both sides of the stem except near the apex where they separate; usually serrated. Leaves oblong-lanceolate to linear-lanceolate and usually slightly crescent shaped; leaves may have a silvery line or red “splotch” in the center along the midvein; most leaves 1.5-2 cm long and longer. Cyathia about 1 mm across. Appendages mostly entire. Styles long and slender. Fruits glabrous. Seeds with 3 transverse ridges; mostly dark grey in color.

Comments 4

Many people have confused E. hyssopifolia, E. hypericifolia, and E. nutans. All three species can be distinguished using the following characters:

Euphorbia hyssopifolia: Stems glabrous or with pilose hairs; stipules shorter than 1 mm erect; cyathia solitary, at most in dense leafy inflorescences.
Euphorbia hypericifolia: Stems always glabrous; stipules longer than 1 mm spreading away from the stem; cyathia in dense leafless inflorescences (a single solitary cyathium is usually present at the node before the nodes holding the dense inflorescences).
Euphorbia nutans: Stems always with some short crinkled hairs (in Texas; may be glabrous elsewhere; see note on hairs for E. nutans); stipules shorter than 1 mm erect; cyathia solitary, at most in dense leafy inflorescences.

Photography suggestions 5

To get a good ID, I recommend the following:

  1. A habit shot (which will narrow it down to E. nutans and E. hyssopifolia most of the time)
  2. A close up of the UPPER sides of apical stems
  3. A close up of the very base of the plant including basal branches (particularly any that are small and hairy)

An observation with these three photos should be identifiable except under the most stressful circumstances (for the plant). Ultimately, the plants are most easily identified by their seeds, which can be extracted by a process described here.

Sources and Credits

  1. (c) Nathan Taylor, some rights reserved (CC BY-NC-SA), uploaded by Nathan Taylor
  2. (c) Nathan Taylor, all rights reserved, uploaded by Nathan Taylor
  3. (c) Nathan Taylor, some rights reserved (CC BY-NC), uploaded by Nathan Taylor
  4. (c) Nathan Taylor, some rights reserved (CC BY-SA), http://www.inaturalist.org/guide_taxa/346752
  5. (c) Nathan Taylor, some rights reserved (CC BY-SA)

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