Ridged-seed Sandmat

Euphorbia glyptosperma

Description 2

Plants prostrate (ascending in shade or competition) annuals; glabrous; generally less than 4 cm tall glabrous; often spreading to 20-30 cm wide, rarely more than 30 cm; plants form mats of 1 to many layers of stems. Largest internodes up to 2 mm in diameter at base. Stipules divide into thread-like strands. Leaves oblong; margins often slightly serrated but difficult to notice without magnification; bases significantly unequal; sides typically not curved. Cyathia small, around 0.5 mm across. Appendages present. Fruits around 1.5 mm long. Seeds deeply ridged.

Habitat and Distribution 2

Common and widespread (Turner et. al., 2003; SRSC) in various soils but tends to prefer dry, disturbed, sandy soils. This species is especially common after an area has been tilled. It is generally only weedy if an area is not watered. For this reason, it is not often a lawn and garden weed if an owner provides supplemental watering (which opens the door for at least four other species), but is often a non-problematic weed in dryland cotton fields, gardens with little to no irrigation and/or sandy soil.

Comments 2

Euphorbia glyptosperma is easily distinguished from other weedy species by its lack of hair, oblong leaves, distinct stipules, and prostrate habit. Perhaps most similar to E. maculata, E. glyptosperma is easily distinguished by its lack of hair and lack of maculation on leaves. Euphorbia maculata is hairy, and often has a maculation on each leaf.

Throughout Texas, Euphorbia glyptosperma looks superficially most similar to Euphorbia serpillifolia (primarily rocky soils), E. geyeri (a sand dune species) and E. abramsiana (a Trans-Pecos endemic). Euphorbia serpillifolia has seeds that aren't so prominently ridged, usually winged and upright stems (but this varies), leaves more deeply serrated and more asymmetric, generally longer appendages, and rounder fruits. Euphorbia serpillifolia and E. glyptosperma can be difficult to distinguish even with good photos, but the other species are easier. Euphorbia geyeri has entire leaves, almost equal leaf bases, larger cyathia and fruits, and smooth seeds. The stems are also usually redder in E. glyptosperma, but this is a variable character. Euphorbia abramsiana has hairs on the stems and often has non-continuous maculations (broken up into many irregular splotches) on the leaves.

Sources and Credits

  1. (c) Nathan Taylor, some rights reserved (CC BY-NC), uploaded by Nathan Taylor
  2. (c) Nathan Taylor, some rights reserved (CC BY-SA), http://www.inaturalist.org/guide_taxa/346773

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