''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 of central

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

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 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 ...

; of West Africa) and ''Ficus geocarpa'' (Moraceae; of the Malay Peninsula) and ''Ficus unciata'' var. ''strigosa'' (also of Malaya) have larger subsurface panicles, 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 ar ...

, 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