Plant material: Samples of B. gibraltarium were gathered in November 1995 during the fruiting period (F), in May 1996 during the pre-flowering period (PF), in July 1996 during the full flowering period (FF), and in September 1996 during the late flowering period (LF) from El Zumbel area (UTM: 30SVG3278) . Every sample consisted in the whole aerial parts of five single plants growing wild near one to another. Once the plants reached the laboratory, they were airdried for seven to 15 days, and separated by parts, i.e., leaves, stems, umbel rays and, when present, fruits.

In the leaf oils, sabinene (12.0-33.9%) and limonene (7.8-23.4%) were the main components, the sabinene level being minimum in full flowering and maximum in fruiting. In stem oils, sabinene (4.7-21.6%) and 2,3,4-trimethylbenzaldehyde (9.3-13.6%) were the main components, the sabinene level being minimum in pre-flowering and maximum in full flowering. In umbel ray oils, sabinene (20.7-43.1%) was the first component in all the phenological periods, followed by alpha-pinene (7.3-28.2%). Both monoterpenes increased their levels in late flowering and reached minimum amounts in fruiting.

Talauma ovata was collected from October 2003 to February 2005. Leaves and trunk bark from the same set of plants were collected in the four seasons: spring (October 15th, 2003), autumn (April 10th, 2004), winter (July 17th, 2004) and summer (February 15th, 2005). In addition, trunk bark was also collected on January 22nd, 2004 (summer). The plant material was harvested from wild-growing population in Santos Dumont City, Minas Gerais State, Brazil, (21° 28′ 03″ S, 43° 39′ 26″ W), at 1000 m of altitude.

In each season the composition of trunk bark oils was similar to leaf oils, with mainly quantitative differences. However considerable seasonal variation was observed. Significant levels of monoterpenes were found only in autumn. The content of oxygenated sesquiterpenes was highest in samples of spring (October) and decreased in summer (January and February), reaching the lowest level in autumn (April) and increasing again in winter (July). In trunk bark oils the main constituents were: spathulenol, alpha-eudesmol, linalool, trans-beta-guaiene and caryophyllene oxide. The major component in all samples of trunk bark was spathulenol. Its level was highest in October (46.8%), decreased in January (33.3%), remained stable in April and July (18.0%) and increased again in February of next year (27.7%). Levels of alpha-eudesmol were high in spring (13.0%) and autumn (11.5%). Linalool peaked only in April, while trans-beta-guaiane peaked in July (11.1%). Caryophyllene oxide ranged between 10.7-2.0%. The level was highest in January, decreased regularly until July and increased slightly again in October. In leaf oils the main components were: spathulenol, germacrene B, germacrene D, caryophyllene oxide and viridiflorol. Spathulenol was the major component in sample of spring (34.4%), but decreased gradually until winter, when reached the lowest level (9.4%). Caryophyllene oxide showed a similar pattern, varying from 14.1% (spring) to 2.4% (winter). An inverse effect was observed for viridiflorol, which increased from 0.1% in October to 13.7% in July. Important levels of alpha-eudesmol were observed in October (12.3%) and February (9.5%). The percentage of germacrene D was highest in summer, while germacrene B showed high amounts in autumn and winter. The seasonal changes in oil composition of T. ovata can be associated with cycle of life of plant (flowering, fruiting and vegetative stages) and climatic parameters such as intense raining in the spring and summer.