J. Jpn. Bot. 93(3): 147–154 (2018) Comparative Anatomy of the Seeds of Monotropastrum humile and Monotropa uniflora (Monotropoideae, Ericaceae) Chiharu UGAJIN and Yasuhiko ENDO* Graduate School of Science and Engineering, Ibaraki University, 2-1-1, Bunkyo, Mito, 310-8512 JAPAN *Corresponding author:
[email protected] (Accepted on November 27, 2017) A comparative anatomical study on the endozoochorous seeds of Monotropastrum humile (D. Don) H. Hara in comparison to the wind-dispersed seeds of Monotropa uniflora L. was conducted. The endozoochorous seeds were ovoid and had lignin-rich cell walls. These cell walls were six times thicker than those of wind-dispersed seeds. The ovoid seed was hypothesized to be an ancestral characteristic of the subfamily Monotropoideae (family Ericaceae). The evolution from the ancestral character state to the derived state (seeds having wing-like seed coats) was presumed to have happened four times independently in the subfamily. Key words: Endozoochory, lignin, Monotropastrum humile, Monotropa uniflora, seed coat, wind dispersal. The subfamily Monotropoideae (Ericaceae) crickets eat the berry and excrete the undigested is composed of 13 species, which are seeds as part of their feces, which then germinate achlorophyllous epiparasitic plants, and are (Suetsugu 2014, 2017). This type of seed classified into 10 genera (Wallace 1987, Qin and dispersal is called endozoochory (Cochrane et al. Wallace 2005). These plants have fine seeds, and 2005). their fruits are berries in five genera and capsules In recent moleculer phylogenetic studies in five genera (Wallace 1975). (Bidartondo and Bruns 2001, Tsukaya et al. Three species of Monotropoideae are 2008), Monotropa unifloraand Monotropastrum distributed in Japan, namely, Monotropa humile were united into a monophyletic clade h y p o p i t y s L .