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.

Aerial parts of T. fontanesii were collected during June 2004, in full blossom, in the Province of Tlemcen in four locations: Sidi-snoussi, Remchi, Sebdou et Sebaa-chiouki and again, during June 2005, in the last location.

The yield of oil obtained from the aerial parts of Thymus fontanesii harvested in the Province of Tlemcen (Algeria), calculated on dry material basis,varied slightly from station to station: Sebaa-chiouki = 5.20%, Sebdou = 5.25%, Sidisnoussi = 5.32%, Remchi = 5.46%. The composition of the four samples was quite similar, carvacrol (66.7-69.5%) being by far the main component. Other constituents, present at appreciable contents, were p-cymene (6.1-9.1%), gamma-terpinene (6.0-9.6%), linalool (3.0-4.0%), alpha-pinene (2.5-3.0%), myrcene (1.2-1.5%), and alpha-terpinene (1.1-1.4%). Conversely, thymol accounted only for 0.6-0.7% of the composition. Moreover, a sample harvested at Sebaa-chiouki, in June 2005, produced on oil with the same composition (68.3% of carvacrol). Obviously, aerial parts of T. fontanesii from the province of Tlemcen produced an oil whose composition differed substantially from that of the oil obtained from the same species harvested in Setif province and Constantine area (Algeria), dominated by thymol (67.8% and 68.2%, respectively).

Herbal parts were collected from A = Eskisehir: Suluagac village in Turkey, altitude 1100 m, in July 1990 and B = Corum: Osmancik, Berk village in Turkey, altitude 580-600 m, on 22 June 1993.

One chemotype (Suluagac village, Eskisehir, Turkey) contained carvacrol (21.59%), p-cymene (17.80%) and thymol (14.10%); and the other chemotype (Berk village, Corum, Turkey) contained alpha-terpinyl acetate (23.80%), borneol (12.85%), linalool (13.67%) and thymol (11.31%) as major constituents.

Plant materials were collected from the following localities in north western Turkey. A = Trabzon: Caykara, Soganli dag on July 28, 1994; B = Bayburt: Caykara, Mohakambo yaylasi on July 25, 1994; C = Trabzon: Koprubasi, Vizara yaylasi on July 20, 1994.

One hundred and four compounds were identified representing 97.5-99.5% of the total components detected in thymol/carvacrol (50.14/10.67%), thymol/linalool (23.14/20.24%) and linalool/alpha-terpinyl acetate/geraniol (21.55/16.70/11.17%) rich oils.

Aerial parts of the plant were collected from four localities: A = Kirklareli: Karadere in May 1991; B = Kirklareli: Karahamza Village in May 1990; C = Kirklareli: Evciler Village on 13 June 1993; D = Kirklareli: Korukoy on 25 May 1994

The four oils obtained from plants collected in different localities of the same region gave quite different compositions as follows: A: thymol (10.5%), 1,8-cineole (9.96%), p-cymene (9.48%), carvacrol (5.28%); B: beta-caryophyllene (29.50%), carvacrol(20.59%); C: thymol (34.7%), beta-caryophyllene (12.74%), carvacrol (5.24%); D: beta-caryophyllene (56.48%), germacrene D (11.12%), carvacrol (4.85%). Since the identities of the plant materials were checked repeatedly, any misidentification is ruled out. Except for A and C, all the other materials showed beta-caryophyllene as the major constituent. Carvacrol (20.59%) was present in good amount in the oil of B. In A, however, high percentages of 1,8-cineole (10%) and p-cymene (9.5%) were significant. This oil contained only a trace amount of beta-caryophyllene. Four isomeric caryophyllene alcohols were detected in the oil B. The results clearly indicate that the oil of T. striatus var. interruptus has no consistency and we can safely suggest that there are at least three chemotypes, namely thymol/1,8-cineole/p-cymene-type; thymol/beta-caryophyllene-type; and beta-caryophyllene-type, of this species.