Monographs Details: Tibouchina steyermarkii Wurdack
Authority: Steyermark, Julian A. & Maguire, Bassett. 1972. The flora of the Meseta del Cerro Jáua. Mem. New York Bot. Gard. 23: 833-892.
Family:Melastomataceae
Description:Latin Diagnosis - T. fraternae N. E. Brown affinis, foliis uninervatis supra non squamatis differt. Ramuli obtuse quadrangulati demum teretes sicut foliorum costae subtus hy-panthiaque dense squamis lanceatis acutis imperspicue ciliolatis plerumque 0.7-1.5 (-2) × 0.25-0.7 mm ornati; petioli 0.2-0.3 cm longi; lamina 1-1.3 × 0.4-0.5 cm oblongo-elliptica basi apiceque acuta, rigida et squamis appressis ciliolata, supra glabra et striolata, subtus in superficie squamis ovatis vel lanceatis acutis 0.2-0.5 (-0.8) mm longis sparse obsita, uninervata nervis secundariis nervulisque invisis; flores 5-meri in ramulis lateralibus brevibus terminales; hypanthium fructiferum 5-6 mm longum ad basim bracteis duabus foliaceis liberis 4-8 mm longis investum; torii squamae extus usque ad 3 mm longae; calycis lobi 4 mm longi lanceati persistentes extus dense squamis lanceatis induti intus glabri; petala staminaque ignota; stigma truncatum; stylus 10 × 0.3 mm glaber; ovarii apex dense squamis 1.5-2 mm longis anguste lanceatis acuminatis ornatus.

Discussion:

Fig 11.

Tibouchina fraterna has larger (2-4 X 1-2 cm) 3-nerved leaves with 4-8 irregular longitudinal rows of free squamose tips between the veins. In the striolate upper surfaces of the leaves, there is a resemblance to T. sipapoana Gleason; however that species has prominently fringed apically rounded scales which overlap and completely cover the lower leaf surfaces, as well as rounded hypanthial scales. Despite the lack of petals and stamens, T. steyermarkii is readily recognizable as belonging to the group of tepuí species which are sharply defined vegetatively (Mem. N. Y. Bot. Gard. 10(1): 104. fig. 11. 1958); among these relatives, T. fraterna shows the closest resemblance in squamal shape.