Bocageopsis multiflora leaves were collected in the Adolpho Ducke reserve, Km 26 Manaus - Itacoatiara highway, in the State of Amazonas, Brazil. This species was collected in the rainy (April 2010) and dry seasons (September 2010).

The main constituent of the oil collected in the rainy season was bisabolene (13.2%), while the main constituent in the dry season was spathulenol (16.2%). The highest yield (0.3%) was obtained for the oil collected in the rainy season.

Leaves were collected from in Botucatu/SP, Brazil. 'Point 1' is the Botanical Garden of UNESP classified by semideciduous seasonal forest 1 (SSF 1), 22° 53′ 10.97″ S 48° 29′ 48.92″ W and 888 m a.s.l. The same trees were observed on all points, during the seasons.

Copaiba plants from semideciduous seasonal forests show differences into the phytochemical profile obtained in dry and wet seasons, with presence of monoterpenes alpha-thujene, o-cymene, (Z)-beta-ocimene, (E)-beta-ocimene, gamma-terpinene and terpinolene in point 1 (in the wet season), while Cerrado strictu sensu did not show significant differences in chemical composition of volatile compounds (only alpha-cadinol and seychellene showed significant differences).

The leaves of Cunila angustifolia which were collected in the Santa Catarina state, Brazil in October (2001), January (2002), April (2002) and July (2002).

The oxygenated compounds were found with high concentration (winter- 77.0%, spring- 84.1%, summer- 82.2% and autumn76.2%). Seasons with low temperature showed increasing in the concentration non-oxygenated compounds (winter- 18.6%, spring- 13.6%, summer- 10.2% and autumn- 19.2%). There is little variation in the main component (pulegone) of the oil on different seasons. The spring oil showed a high concentration this monoterpene (72.3%). The other season's oils showed increasing amounts in the concentration of isomenthone and neomenthol. Winter and autumn oils showed a significant increase in the concentration of beta- caryophyllene and bicyclogermacrene.

Eucalyptus urophylla and E. grandis were collected in January (summer) and August (winter) 2006 at the mature vegetative state from Goiania city Brazil, and identified by one of the authors (E.P.F.). Leaves from 5-11 randomized individual plants of the same age representing the local population were collected as homogenous samples in each season, dried at room temperature.

The results were submitted to Principal Components and Clusters Analysis which enabled four groups of oils to be distinguished with regard to specimens and harvest seasons: clusters I and II with only E. grandis samples collected in the cold and dry winter and the hot and humid summer, which were characterized by a high percentage of isoleptospermone (9.6% and 13.2%), alpha-pinene (12.2% and 24.7%), p-cymene (20.5% and 14.5%), and alpha-terpineol (14.3% and 4.9%), respectively; clusters III and IV only associated with E. urophylla samples collected in summer and winter with 1,8-cineole (36.6% and 44.7%) and alpha-terpinyl acetate (7.0% and 11.7%) rich oils.

Eucalyptus urophylla and E. grandis were collected in January (summer) and August (winter) 2006 at the mature vegetative state from Goiania city Brazil, and identified by one of the authors (E.P.F.). Leaves from 5-11 randomized individual plants of the same age representing the local population were collected as homogenous samples in each season, dried at room temperature.

The results were submitted to Principal Components and Clusters Analysis which enabled four groups of oils to be distinguished with regard to specimens and harvest seasons: clusters I and II with only E. grandis samples collected in the cold and dry winter and the hot and humid summer, which were characterized by a high percentage of isoleptospermone (9.6% and 13.2%), alpha-pinene (12.2% and 24.7%), p-cymene (20.5% and 14.5%), and alpha-terpineol (14.3% and 4.9%), respectively; clusters III and IV only associated with E. urophylla samples collected in summer and winter with 1,8-cineole (36.6% and 44.7%) and alpha-terpinyl acetate (7.0% and 11.7%) rich oils.

Plants from Horto de Plantas Medicinais of Universidade Federal de Lavras (UFLA) were cultivated in the form of a randomized block with six replications in an experimental field at Setor de Horticultura, UFLA, in Lavras city (S 21° 14′, W 44° 59′, 920 m). Samples were collected four times at 3-month intervals from March to December 2004.

There was a significant difference for oil contents in the different seasons. The lowest oil content was obtained in the summer (about 50% inferior to the other seasons). Methyl (E)-cinnamate was obtained as the major compound (86-90%) of the 14 identified components.

The aerial parts of M. biflora collected during November 1993 and June 1994 were used for the investigation.

The major constituents of the oil were neral (25.3-32.2%) and geranial (26.7-41.3%). The oil produced in the winter was found to contain higher amounts of oxygenated monoterpenes than the oil produced in the summer.