Iochroma arborescens

'akneestis' / 'aknistis'), meaning 'backbone',[3] possibly in reference to the backbone-like, white, longitudinal stripes running up the centre of each green patch on the exterior of the corolla.

[5] Concerning the very close relationship of Iochroma with the monotypic genus Acnistus, it is of the utmost importance to make intensive collections properly annotated in southern Ecuador and northern Peru; in this region native populations grow, with yellow-coloured corollas which appear to be intermediate between both genera.

For example, Iochroma ellipticum and I. confertiflorum, two large-flowered species that were transferred from Acnistus by Hunziker,[14][13] have valvate bud aestivation and lack a strongly accresent calyx.

(S. D. Smith, personal observation) indicate that they share with Acnistus a conspicuous green mark on the inner surface of the corolla lobe, which fades to yellow as the flower ages.

In Puerto Rico and the United States Virgin Islands, it is classified by the US Department of Agriculture as a native plant species.

[20] Some sources claim that the attractive fruits are edible (though causing diarrhea if consumed to excess) : others that they are inedible, due to bitterness or insipidity.

[25] The patois name Tabak djab (Devil's tobacco) may be significant in this context, suggesting that the leaves of the plant may have been smoked.

Compare the Spanish name Tabaco del Diablo – also meaning Devil's Tobacco – applied to Lobelia tupa, a narcotic plant smoked by the Mapuche of Chile.

[30] Ayensu (1981) lists alkaloids, glycosides, organic acids, saponins and tannins as constituents of plant material collected in Trinidad and Dominica.

The essential oil from leaves harvested from a population of I. arborescens growing in the vicinity of Mérida, Venezuela, has been isolated by hydrodistillation.

The chemical composition of the leaf oil thus recovered was determined by GC-FID and GC-MS and the most abundant components found to be (Z)-hex-2-enal (40.7%) and estragol (25.6%).

This volatile is almost undetectable by the human nose, but (as revealed by experiments) readily detectable by the olfactory sense of honey bees.

Dunalia spinosa , wild plant, growing near the town of Chachas in southern Peru (The plant now known as Acnistus arborescens has, in the past, been assigned to the closely related genus Dunalia – among many other genera.)
Flowers of Acnistus arborescens , viewed from beneath, revealing taxonomically significant 1.) short anthers and 2.) yellowish-green marks on interior of corolla lobes. Wild plant, Volcan Mombacho , Nicaragua .
The flowers of certain species of Iochroma bear a marked similarity to those of Acnistus – note especially green stripes on interior of white corolla lobes ( Iochroma umbellatum – cultivated plant, University of California Botanical Garden , Berkeley, California )
Branch of Acnistus arborescens bearing simultaneously flowers and fruit – both ripe and unripe. Wild plant, Sumaco Napo-Galeras National Park , Ecuador – where the plant has the common name of Gallinero .
Trunks of mature specimen of Acnistus arborescens showing corky, grey bark. Cultivated plant, Mildred E. Mathias Botanical Garden at UCLA , Westwood , Los Angeles , California .
The fragrant flowers of Acnistus arborescens , redolent of a rare volatile attractive to honey bees.