APS_October 2018

C arob

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Janine and Joun), recalling the traditional Mediterranean agro-ecosystem where olive and carob trees were inter-planted. Many of these trees were in good shape while others were partially destroyed by various anthro- pogenic acitivities. The immense majority of these trees did not recieve irrigation or other agricultural practices.  Most of the surveyed carob trees were still productive, except seven trees found during the survey without pods and were considered by farmers as male trees. Although flower type was not addressed in this study, at least eight trees of the 59 studied and mostly lo- cated in Mount Lebanon were hermaphrodite with some inflorescences carrying pistillate flowers and others carrying staminate flow- ers, or with inflorescences carrying her- maphroditic flower. Normally, dried pods are harvested in September and processed to produce carob molasses also called “black honey” or “debs”. According to the grow- ers, only a few trees were grafted, such as the one found in Kefraya (designated as Kefraya NLC1) and the one called Rihani (designated as Rihani NLC1). Most of these centennial trees were thought to be subnatural and as- sumed to be derived initially from seedlings growing spontaneously in natural landscapes or in plantations.  Information given by the growers and mu- nicipalities indicates the carob trees consid- ered in this study may have been 150 to 250 years old. The oldest tree might be the one found in Amioun ( Amioun NLC2 ) which may have been more than 200 years, followed by the tree of Deir Janine ( Deir Janine NLC1 ) and the one of Kefraya ( Kefraya NLC1 ) with more than 150 years. Some centennials are located near some archeological troves, ru- ins and ancient monasteries, indicating their long history in the country. Tree characteristics  Trees had large foot circumferences, from 2 m (e.g. Wadi Al Houjair SLC2 ) to 8.2 m (e.g. Amioun NLC2 ) (Supplementary Table 2, Fig. 2). Trunk circumferences ranged be-

0.3 (P < 0.05), except for those exhibiting collinearity, were included in the PCA to se- lect the most representative ones, according to Sleighter et al. (2010). Selected variables were identified by an optimal PCA solu- tion that included Bartlett’s sphericity test, a KMO (Kaiser-Meyer-Olkin) test, com- munalities, correlations with principal com- ponents, and maximum explained variance (Martínez-González et al ., 2006). With the eight variables accounting for the maximum fraction of variance in the original dataset (Supplementary Table 6; Fig. 4), accessions were subjected to agglomerative hierarchi- cal cluster analysis (unsupervised clustering, Ward’s method) based upon squared Euclid- ean distance. Classification was carried out using an agglomerate algorithm (Everitt, 1980). The number of groups was judged visually based on the resulting dendrogram. After groups were defined, one-way analyses of variance were used to detect differences in quantitative traits among the previously established groups. To detect geographic pat- terns of variation in pod morphology, a clus- tering analysis following Ward’s method was performed using R v.3.2.3. Results General status of the carob centennials  Our study included 59 centennial carob trees growing in 31 locations across the country distributed in Mount Lebanon (26 trees), North Lebanon (13 trees), South Leb- anon (10 trees) and Beirut (10 trees) (Fig. 1). Trees were found along the littoral and up to 545 m of altitude (Marouahine in the South). Minimum winter temperature varied between -3.8°C and 3.5°C, while the maximum sum- mer temperature varied between 34.8°C and 38.9°C. The annual rainfall was between 491 mm (Wadi Al Houjair in the South) and 920 mm (Douma in the North). Most of centen- nials are growing as scattered trees on road edges e.g. Nahr Ibrahim, family gardens and yards, and in the remaining maquis in some area e.g. Joun. On the other hand, some car- obs were found in olive groves (e.g. Deir