''Harmsiopanax ingens'' of the Gensing, or Ivy Family (Araliaceae), is a very spiney palmlike mesocaul

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

endemic to the

montane rainforests Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

of central

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

which bears a terminal rosette of deeply lobed, meter-wide (3.25-foot wide) dentate margined, peltate leaves on equally long petioles. It ultimately attains a height of eighteen meters (59 feet), at which point it bears a huge

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are of ...

of flowers five meters (16.5 feet) high and equally wide; the largest above ground inflorescence of any dicot plantW.R. Philipson, "A Revision of Harmsiopanax" BLUMEA Vol. 21 (1973) # 1 pp. 84-85 (although ''Caloncoba flagelliflora'' (

Achariaceae Achariaceae is a family of flowering plants consisting of 32-33 genera with about 155 species of tropical herbs, shrubs, and trees. The APG IV system has greatly expanded the scope of the family by including many genera previously classified in F ...

; of West Africa) and ''Ficus geocarpa'' (Moraceae; of the

Malay Peninsula The Malay Peninsula (Malay: ''Semenanjung Tanah Melayu'') is a peninsula in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area ...

) and ''Ficus unciata'' var. ''strigosa'' (also of Malaya) have larger subsurface

panicles A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are o ...

, each about nine meters (thirty feet) in length. H. ingens' panicles are very unusual; the ultimate twigs being

spikes The SPIKES protocol is a method used in clinical medicine to break bad news to patients and families. As receiving bad news can cause distress and anxiety, clinicians need to deliver the news carefully. By using the SPIKES method for introducing a ...

each bearing about fifty tiny umbels, each

umbel In botany, an umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs. The word was coined in botanical usage in the 1590s, from Latin ''umbella'' "p ...

with 8 to 20 minute flowers. So panicle, spike and umbel are all represented in a single inflorescence. ''Harmsiopanax ingens'' is

monocarpic Monocarpic plants are those that flower and set seeds only once, and then die. The term is derived from Greek (''mono'', "single" + ''karpos'', "fruit" or "grain"), and was first used by Alphonse de Candolle. Other terms with the same meaning are ...

, and again the largest such plant among dicots. H. ingens was discovered in 1973 by W. R. Philipson.Philipson loc.cit. Its native name is "makua".

References

{{Taxonbar, from=Q5659656 Araliaceae