|Spurrey, Spergula arvensis, Kelburn, Wellington, New Zealand.|
|Spergula arvensis. A, B, nodes and leaf bases, showing pale pinkish triangular stipules (circled); C, an inflorescence; D, bud and open flowers, the latter with two anthers missing.|
The leaves are in opposite pairs, but each leaf sports a branch with suppressed internodes, making what appears to be a whorl of leaves at each node (A above). There's a broadly triangular membranous stipule between the leaves of a pair on each side of the stem (circled in B above), which sometimes drops off (A above).
I noticed something interesting when I was preparing the images. The plant was in full flower when I collected it, but the flowers closed in the semi-shade of my office. I resigned myself to not having open flowers to illustrate this post. However, the light from a single pass of the flatbed scanner on an inflorescence with closed flowers (C in the picture above) seemed to be enough to open them again quite quickly (bottom right, above). I'll follow this observation up soon.
Judd, W.S.; Campbell, C.S.; Kellogg, E.A.; Stevens, P.F.; Donoghue, M.J. 2008: Plant systematics a phylogenetic approach. Sinauer, Sunderland, Massachusetts.
Webb, C. J.; Sykes, W. R.; Garnock-Jones, P. J. 1988: Flora of New Zealand. Vol. IV. Christchurch, Botany Division DSIR.