The karuka (''Pandanus julianettii'', also called karuka nut and ''Pandanus'' nut) is a species of tree in the screwpine family (

Pandanaceae Pandanaceae is a family of flowering plants native to the tropics and subtropics of the Old World, from West Africa to the Pacific. It contains 982 known species in five genera, of which the type genus, ''Pandanus'', is the most important, with s ...

) and an important regional food crop in

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

. The nuts are more nutritious than

coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family (biology), family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, ...

s, and are so popular that villagers in the

highlands Highland is a broad term for areas of higher elevation, such as a mountain range or mountainous plateau. Highland, Highlands, or The Highlands, may also refer to: Places Africa * Highlands, Johannesburg, South Africa * Highlands, Harare, Zimbab ...

will move their entire households closer to trees for the harvest season.

Description

The species was originally described in 1908 by

Ugolino Martelli Ugolino Martelli (1860–1934) was an Italian botanist, biologist, and mycology, mycologist. Martelli is known for his studies of and contributions to the systematics of the tropical genus ''Pandanus'' and his taxonomic definition of the flora o ...

from only a few

drupe In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pip'' (UK), ''pit'' (US), ''stone'', or ''pyrena'') of hardened endocarp with a seed ...

s in the collections of the

Royal Botanic Gardens, Kew Royal Botanic Gardens, Kew is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. An internationally important botanical research and education institution, it employs 1,10 ...

He was hesitant to describe it as a new species from only that, but the characteristics were so salient he published his description. The tree is

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

(individual plants either have male flowers or female ones), with male trees uncommon compared to females. It reaches in height, with a grey

trunk Trunk may refer to: Biology * Trunk (anatomy), synonym for torso * Trunk (botany), a tree's central superstructure, and the stem of woody plants * Trunk of corpus callosum, in neuroanatomy * Elephant trunk, the proboscis of an elephant Comput ...

of in diameter and supported by prop roots or flying

buttress root Buttress roots, also known as plank roots or stilt roots, are large, wide roots on all sides of a shallowly rooted tree. Typically, they are found in nutrient-poor tropical forest soils that may not be very deep. They may prevent the tree from fa ...

s up to forty feet (twelve meters) in length and six inches (15 cm) or more in diameter.. The trunk has white mottling and is generally smooth with occasional warts or small knobs as well as rings of

leaf scar A leaf scar is the mark left by a leaf after it falls off the twig. It marks the site where the petiole attached to the stem. A leaf scar is typically found below a branch, as branches come from axillary buds located above leaf scars. Formation ...

s. Inside the trunk is pithy and lacking

cambium A cambium (: cambiums or cambia), in plants, is a tissue layer that provides partially undifferentiated cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant tissue from whic ...

. The top of the tree sometimes branches, producing three or four crowns of leaves. Each crown will produce a single cluster of nuts, typically once every other season. Production is affected by the seasonality of local rainfall.

Leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

spiral up the trunk in

opposite In lexical semantics, opposites are words lying in an inherently incompatible binary relationship. For example, something that is ''even'' entails that it is not ''odd''. It is referred to as a 'binary' relationship because there are two members i ...

pairs. The large leathery leaves are long and wide. The apex of the leaf is

attenuate In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable at ...

and doubly-pleated, with prickles pointing up at the tip and along the

margins Margin may refer to: Physical or graphical edges *Margin (typography), the white space that surrounds the content of a page *Continental margin, the zone of the ocean floor that separates the thin oceanic crust from thick continental crust *Leaf ...

and

midrib A primary vein, also known as the midrib, is the main vascular structure running through the center of a leaf. The primary vein is crucial for the leaf’s efficiency in photosynthesis and overall health, as it ensures the proper flow of material ...

. The leaves are dark green on top and dull cyan underneath. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

on male trees is a densely-branched spadix with a dozen long spikes, each containing many

staminate The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

phalanges. In each phalange is a

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...

3 mm long topped by up to 9

subsessile In botany, sessility (meaning "sitting", in the sense of "resting on the surface") is a characteristic of plant organs such as flowers or leaves that have no stalk. Plant parts can also be described as subsessile, that is, not completely sessil ...

anther The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s. The male flowers are white, and the whole male flowering organ may be up to long. The

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

has a

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