(ProQuest: ... denotes non-US-ASCII text omitted.)(ProQuest: ... denotes formulae omitted.)IntroductionAfter Terra's pioneering descriptions of the different types of homegardens associated with different ethnic groups in the Indo-Malayan region (Terra 1952-53; 1954; 1958), few additional studies were published about Southeast Asian homegardens until the 1980s when homegardens emerged as a major focus of agroforestry research. Much of this research was concerned with describing the architecture, species composition, and functions of homegardens of different ethnic groups in the tropics. Since that time, a considerable number of studies have been published describing the structure, species diversity, and functions of homegardens of ethnic groups in different Southeast Asian countries, including Burma (Terra 1954), Indonesia (Soemarwoto and Soemarwoto 1984; Wiersum 2006), Laos (Kou et al. 1990; The SUAN Secretariat 1990; Dyg and Saleumsy 2004; Nawata et al. 2009), Thailand (Moreno-Black et al. 1996; Jiragorn and Nantana 1999; Nawata et al. 2009; Thanakorn et al. 2010; Kamonnate et al. 2012), and the Philippines (Snelder 2008). There has also been considerable research on homegardens in Vietnam (Le Trong Cuc et al. 1990; Karyono et al. 1993; Hodel et al. 1999; Dao Trong Hung et al. 2001; Luu Ngoc Trinh et al. 2003; Vlkova et al. 2011) but it has mostly been focused on the Kinh (ethnic Vietnamese), the majority ethnic group. Only a very few studies have been done on the homegardens of ethnic minorities. In the case of the Cao Lan, a Tai speaking minority group living in the Northern Mountain region, there are only 2 brief reports (Gillogly and Nghiem Phuong Tuyen 1992; Le Trong Cuc and Rambo 2001) which describe the species composition of their homegardens but not their ecological structure or the functions of the different species.It was in order to obtain information about the structure and species composition and functions of Cao Lan homegardens, that we carried out a short field study in a Cao Lan community in Tuyen Quang province in Northern Vietnam. This case study was done as part of a larger comparative study of the ecological structures of homegardens of different ethnic groups in Northeast Thailand and Vietnam which was designed to assess the relative importance of culture and environment as determinants of agroecosystem structure (Pijika 2014). The aims of this paper are to describe the modal ecological structure of the Cao Lan homegardens, identify all of the plant species grown in these gardens and categorize their functions, and compare the modal structure of the Cao Lan gardens with those of their Kinh neighbors and ethnically related Tai minority groups in Northeast Thailand.BackgroundThe Cao Lan Ethnic GroupThe Cao Lan speak a language belonging to the Tai family of languages. They are one of 54 officially recognized ethnic groups in Vietnam. They are known officially as San Chay (also often called Cao Lan-San Chi). They first immigrated to Vietnam from China beginning in the 1600s. The Cao Lan numbered about 169,000 people in 2009. They are mainly settled in Tuyen Quang, Bac Can, and Thai Nguyen provinces. Settlements of this ethnic group are also scattered in Yen Bai, Vinh Phuc, Phu Tho, Bac Giang, and Quang Ninh provinces (Dang Nghiem Van et al. 2000; Sumitre et al. 2003; Ethnologue: Languages of the World 2013). According to the 1999 census, a few thousand San Chay live in the Central Highlands, mostly in Dac Lac with smaller numbers in Binh Phuoc, Dong Nai, Gia Lai, and Kon Tum provinces (General Statistical Office 2001). It is likely that these people migrated south to the New Economic Zones in the 1980s.According to Gregerson and Edmondson (1998), the Cao Lan-San Chay ethnic group is actually a composite of two groups with two different languages and two nonoverlapping cultures. The Cao Lan language has been classified as a Central Tai language of the Kam-Tai sub-branch of the Tai-Kadai language family, while the San Chay language is Han Chinese. …