Fig. 1

Stems of Cosmosperma polyloba. a Stem with primary rachises. PKUB13501a. Scale bar = 20 mm. b Combined figure of two counterparts of specimen shown in Fig. 1 a, exhibiting stem with primary rachises. Arrow indicating portion enlarged in Fig. 1 c. PKUB13501b (part in dashed box), PKUB13501c. Scale bar = 20 mm. c Enlargement of Fig. 1 (b, arrow), showing conical prickles (arrows) and parallel vertical striations on the stem. Scale bar = 2 mm. d Stem with the widest primary rachis. PKUB13502. Scale bar = 20 mm. e Stem and helically arranged primary rachises with swollen bases. Arrows indicating portions enlarged in Fig. 1 f, g. PKUB13503. Scale bar = 20 mm. f Enlargement of Fig. 1 (e, left arrow), showing conical prickles (arrows). Scale bar = 2 mm. g Enlargement of Fig. 1 (e, right arrow), showing parallel vertical striations (white arrow) and conical prickles preserved as pit-like impressions (black arrows). Scale bar = 2 mm. h Combined figure of part and counterpart of one specimen, showing a stem with primary rachises arranged in irregular helix. PKUB13504a, PKUB13504b (dashed box). Scale bar = 20 mm