Prostrate to decumbent annual or perennial herbs. Basal leaves petiolate Flowers bracteate or not, blue or shades of purple-brown. Calyx 5-partite, enlarged in fruit. Corolla cylindrical to funnel-form or ± campanulate. Throat appendage present. Anthers generally included. Gynobase ± pyramidal. Nutlets 4, dorsal surface glabrous or with protuberances; margins with inflexed wings, entire or not glochidiate.
Hilger et al. (l.c.) have recently described a new genus Microparacaryum (M. Pop. ex Riedl) Hilger & Podlech (Paracaryum sect. Microparacaryum M. Popol in Fl. URSS. 19:602.1953), to include the annual species of Paracaryum and Mattiastrum with small flowers and fruits. In Pakistan these include Paracaryum intermedium and Mattiastrum bungei.
I do not propose following them and merging Paracaryum intermedium and bungei under Microparacaryum. The generic distinction (at least in the Pakistan taxa) between Paracaryum and Mattiastrum is quite clear cut. In the former, the margin of the nutlets are distinctly inrolled to form an aperture; whereas in Mattiastrum the margin of nutlet or wing is flat or slightly inrolled and the aperture is not evident.
As regards the annual Paracaryum intermedium, this is a very variable species throughout its geographical range. Some specimens from Baluchistan with small fruit, and flowers are tall and much branched and suggest they may even be biennials (R. Akhtar 12712; Dick Peddie 317; Khairuddin 117; R.R. Stewart 28309).