Achene 1.6-2.1 mm long, 1.1-1.5 mm wide, dark brown, ellipsoid to broadly obovoid, flattened-trigonous to more or less planoconvex
, the adaxial face slightly concave, more or less cuneate to a sessile base, rounded to the short apiculate apex (the style base persistent as an apiculus 0.1-0.2 mm long, or up to 0.4 mm long but easily broken), finely papillose; style branches stramineous to pale reddish, feathery with elongate papillae.
Table 1 shows the optical design specifications of refractive germanium (planoconvex
) lens, as shown in Figure 1, for the wavelength band (8)-(12) [micro]m, effective focal length of 75 mm with a 9.09-degree field of view, and diameter 33 mm.
The Ramsden eyepiece, consisting of two simple planoconvex
lenses, suffers from lateral chromatic aberration characterized by spurious fringes of color around bright objects far from the center of the field.