Cambridge, Trinity College MS O.2.48 is a late XIV Century herbal which is thought to have been written in Germany. Rene Zandbergen has linked the digital scans on the Voynich.ninja forum.
Herba Salomonis (54v,55r) is the only plant illustrated by a scene extending on two pages. The plant could be Polygonatum Odoratum, Salomon's seal.
The plant is also called Martagon, however Lilium Martagon does not seem to match the description of the plant.
Transcription: Nomen herbe martagon [?]. herba salomonis. alii ventuosa. ebraici vismatore [usmatore?]. alii eam | vocant lunaticam sed non est. hec herba fuit revelata beato domino agustino | a quondam philosopho propter quamdam nobilissimam mulierem quam erat bona deo et humilis et | habebat quamdam filiam quam vexabatur a demonio. et filium suum similiter. et venit ad beatum | agustinum et dixit ei de filia sua atque de filio suo qui vexabantur a dem | onio. et dixit beatus augustinus ut aciperent de hac herba martagon et | suspenderent ad collum eorum. et sic faciunt et liberati sunt. hac herba na | scitur in montibus saxosis. huic florem coceum. et semina eius sunt rotunda | et nigri et parva ut piper. folia sunt similima morsus demonis. | sed sunt minora. huic odorem ut pullegium. eius radix est nigra. et huic | odorem saliunce. vale similiter hec herba suspensa ad collum contra lunati | cos. et si quis eam super se habuit sanguis ei exire non poterit. nec ab inimico | suo superari non poterit. et si quis succus eius biberit pondus drachmas 5 cum suco | aristologie rotunde per iii dies dorm iet | haec herba qui super se habuit diabolus ei non nocebit.
Translation: The name of the plant is Martagon [?], plant of Salomon, some call it Ventuosa, in Hebraic Vismatore [Usmatore?]. | Some call it Lunatica, but it is not [this plant]. This plant was revealed to the blessed lord Augustine | by some philosopher to help a very noble woman who was faithful to God and humble. | She had a daughter who was vexed by the devil, and her son too. She went to the blessed | Augustine and told him of her daughter and of her son who were vexed by the | devil. The blessed Augustine told them to take this plant Martagon and | hang it around their necks. They did so and they were freed. This plant grows | on stony mountains. Its flower is yellow and its seeds are round | and black and small like Pepper. The leaves are very similar to Devil's Bit [Morsus Diaboli] | but are smaller. Its smell is like that of Fleabane [Pullegium]. Its root is black and smells | like Wild Nard [Saliuncus]. Hanged around one's neck, this plant is helpful against | lunatics [lunacy?]. If one wears it upon himself, his blood cannot be spilled and he cannot be | overcome by his enemy. If one drinks five drachmas of its juice with the juice of | Aristolochia Rotunda, he will sleep for three days. | Whoever has this plant upon himself will not be harmed by the devil.
You can find an extensive discussion of the possible identity of this plant on J.K.Petersen's voyichportal blog.