Itoa Hemsl.

First published in Hooker's Icon. Pl. 27: t. 2688 (1901)
This genus is accepted
The native range of this genus is S. China to Vietnam, Central & E. Malesia to New Guinea.

Descriptions

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution
A small genus of two species, with one in China and the other in eastern Malesia and throughout New Guinea from the Bird’s Head Peninsula and reaching Morobe Province in Papua New Guinea, Itoa stapfii (Koord.) Sleumer.
Morphology General Habit
Trees to 35 m (in New Guinea) Plants dioecious or monoecious
Morphology Leaves Stipules
Stipules absent but with intra-axillary buds
Morphology Leaves
Leaves spirally arranged, large, pinnate-veined, margins crenate; petioles relatively long, somewhat pulvinate both at the base and apex
Morphology Reproductive morphology Inflorescences
Inflorescences axillary or terminal, staminate plants with panicles, pistillate plants with solitary, axillary flowers, pedicel elongating in fruit and distinctly articulate above the middle
Morphology Reproductive morphology Flowers
Flowers: calyx lobes 3(–4), valvate, nearly free; petals absent Staminate flowers: stamens numerous; pistillode present, rudimentary
Morphology Reproductive morphology Flowers Gynoecium Pistil
Pistillate flowers: staminodes numerous, ovary superior, placentas (5–)6–8, ovules numerous; styles 6–8
Morphology Reproductive morphology Fruits
Fruit capsular, large, many-seeded, tardily dehiscent from the apex in (5–)6–8 valves, coriaceous exocarp separating both at base and apex from the hard, woody endocarp
Morphology Reproductive morphology Seeds
Seeds numerous, very compressed, winged, vertically arranged, the proper seed small.
Ecology
Itoa stapfii has collected from a range of habitats including primary and secondary rain forest from sea level to 1000 m.
Recognition
The genus can be recognised by the relatively large leaves with relatively long pulvinate petioles (up to 8 cm long) and crenate margins, the unisexual flowers, the staminate flowers having numerous stamens, the pistillate flowers with a superior ovary, and the capsular fruit which is usually longitudinally ridged and then splitting into 6–8 valves with numerous winged seeds.
[TONG]

Sources

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Trees of New Guinea

    • Trees of New Guinea
    • http://creativecommons.org/licenses/by-nc-sa/3.0