<![CDATA[The fitness of many angiosperm plants, including Reutealis trisperma, is affected by the size and number of fruit and seed. However, studies on the fruit and seed morpho-physiology of R. trisperma are still highly limited. This study aimed to identify the variation of locule and seed number besides the fruit and seed morphometric traits of R. trisperma. The number of locules and seeds per fruit was observed in immature, developing R. trisperma fruits. These observations were made by cross-sectioning R. trisperma that was obtained from field collections. Morphometric data collection was subsequently carried out on sampled mature fruits. The results showed that the locule and seed number of the single fruit of R. trisperma ranged from 2 to 4 and 1 to 4, respectively. Trilocular fruits were the most commonly found type. However, some of trilocular fruits were consisted of two seeds (two-seeded fruits) instead of three seeds (three seeded fruits). The proportion of two-seeded fruits was comparable to the three seeded fruits. No significant differences were found in fruit size or weight between two-seeded and three-seeded fruits. However, the seed weight, as well as the kernel weight, were heavier for two-seeded fruits compared to three-seeded fruits. Therefore, it revealed a seed size-number trade-off. These results can enrich the valuable informations related to the growth and development as well as the fitness of R. trisperma. ABSTRAK Daya reproduksi beberapa tanaman angiosperma, termasuk Reutealis trisperma, dipengaruhi oleh ukuran serta jumlah buah dan biji. Namun demikian, masih sangat sedikit penelitian yang telah dilakukan terkait morfo-fisiologi buah dan biji pada spesies tanaman tersebut. Penelitian ini bertujuan untuk mengidentifikasi variasi jumlah lokulus dan biji serta sifat morfometrik buah dan biji dari R. trisperma. Pengamatan jumlah lokulus dan biji per buah dilakukan pada buah muda R. trisperma yang sedang berkembang. Pengamatan dilakukan dengan cara memotong secara melintang R. trisperma yang didapatkan dari koleksi lapangan. Pengumpulan data morfometrik kemudian dilakukan pada buah matang yang diambil sebagai sampel. Hasil penelitian menunjukkan bahwa jumlah lokulus dan biji dari satu buah R. trisperma berkisar antara 2 hingga 4 dan 1 hingga 4, berturut-turut. Buah trilokular adalah jenis buah yang paling umum dari spesies ini. Namun, beberapa buah trilokular terdiri dari dua biji (buah berbiji dua) bukan berisi tiga biji (buah berbiji tiga). Proporsi buah berbiji dua sebanding dengan buah bebiji tiga. Sementara itu, tidak ada perbedaan ukuran buah maupun bobot buah antara buah berbiji dua dan buah berbiji tiga. Di sisi lain, bobot per biji serta bobot per kernel lebih berat pada buah berbiji dua dibandingkan buah berbiji tiga. Hasil tersebut membukitkan adanya hubungan berkebalikan antara jumlah dan ukuran biji. Hasil penelitian dapat memperkaya informasi mengenai pertumbuhan dan perkembangan tanaman serta fitness pada spesies R. trisperma. Kata kunci: Alokasi sumber, Biodiesel, Kemiri sunan, Lokus hampa, Morfometrik]]>
