Mesonsidereos, the Javanese Metal-Sapped Tree

Mesonsidereos is a cryptobotanical "metal-sapped" tree with "an iron wire that comes out of the root, and rises to the top of the tree," supposed in some accounts to grow on the island of Java, one of the Greater Sunda Islands in modern Indonesia, formerly the Dutch East Indies. Further to simply possessing a ferrous core, the lore states that any who wear a piece of this tree become themselves impenetrable by iron.

The story of the tree appears in Richard Folkard's Plant Lore (1884), where it is attributed to William Fleetwood, the Bishop of Ely, and his Curiosities of Nature and Art in Husbandry and Gardening, a 1707 English-language translation of Pierre Le Lorrain, l'Abbé de Vallemont's Curiositez de la Nature et de l'Art sur la Végétation; in l'Abbé de Vallemont's work, the story of the tree is, in turn, attributed to Jules-César Scaliger's Exotericarum Exercitationum (1557), a critique of Jérôme Cardan's De Subtilitate (1550), and is plainly stated to have been made as a joke. It is also of note that Scaliger's reference to Java is actually to Greater Java (Java Major), which would have been known from the accounts of Marco Polo, who stated from hearsay that it was the largest island in the world.

Folkard also attributes a detail about the tree having "fruit impenetrable by iron" to Hieronymus Hirnhaim's De Typho Generis Humani (1676).^[H]

Sources

• Scaligeri, Julii Caesaris (1557), "Exercit. CLXXXI: Plantæ peregrinæ" (in Latin), Exotericarum Exercitationum liber quintus decimus de Subtilitate ad Hieronymum Cardanum, Lutetiae (Paris): Ex officina typographica Michaelis Vascosani, p. 248, https://babel.hathitrust.org/cgi/pt?id=ucm.5325859584&view=1up&seq=517 
  

  27. Arbor [μηντξοἱδηως].

  GR AE C V M fortassè nomen à nobis inditũ plus historiæ conueniet, quam ingenio nostro. Tam enim est prop mendaciũ, quàm nos à uoluntario mendacio alieni. Animi tamen gratia reponetur hîc. In Iaua maiore, aiunt, raram esse arborem, cuius medulla ferrea sit; exilis illa quidē, cæterum porrecta ab imo ad summum plātæ fastigium. Ex ea frustum qui gerat, ferro esse impenetrabilem.

• Hirnhaim, Hieronymus (1676), "Caput X." (in Latin), De Typho Generis Humani, sive Scientiarum Humanarum, Inani ac Ventoso Tumore, Difficultate, Labilitate, Falsitate, Jactantia, Praesumptione, Incommodis, et Periculis, Pragae: Typis Georgij Czernoch, p. 120, https://archive.org/details/bub_gb_IF4Q_5UV3PAC/page/n133 
  

  XI. In vegetabilium regno quanta non occurrunt miracula? [...] In Java majore datur quæedam herba, cujus medulla est ferrea ab imo usq; ad summum fastigium, fructum quoq; gignit ferro impenetrabilem.

• l'Abbe de Vallemont (1734), "Diverses Végétations curieuses" (in French), Curiositez de la Nature et de l'Art sur la Végétation, Bruxelles: Jean Leonard, p. 240, https://www.biodiversitylibrary.org/item/314735#page/290/mode/1up 
  

  16. Scaliger, contre Cardan plaisante sur l’Arbre appellé [μηνωοιδηως]. On dit que cet Arbre: croit dans l’Isle de Java, où il est fort rare. On ajoûte, qu’au lieu de moüelle, c’est un sil de fer, qui part dela racine, & qui monte jusqu’au coupeau de l’Arbre. Mais le plus beau, c’est que quiconque porte sur soi un morceau de cette mouelle ferrugineuse, il devient impénétrable à quelque épée, ou fer que ce foit. Cela, dit Scaliger, approche autant du menfonge, que nous avons dessein de nous en éloigner. Tam enim est prope mendacium, quàm nos à voluntario mendacio alieni. Exercit. 181. Distinct. 27. Pag. 496.

• Folkard, Richard (1884), "Wondrous Plants." (in English), Plant Lore, Legends, and Lyrics, London: Sampson Low, Marston, Searle, and Rivington, Crown Buildings, 188, Fleet Street, p. 123, https://www.gutenberg.org/files/44638/44638-h/44638-h.htm#page-123 
  

  In Bishop Fleetwood’s curious work, to which reference has already been made, we find many extraordinary trees and plants described, some of which are perhaps worthy of a brief notice. He tells us of a wonderful metal-sapped tree known as the Mesonsidereos, which grows in Java, and even there is very scarce. Instead of pith, this tree has an iron wire that comes out of the root, and rises to the top of the tree. “But the best of all is, that whoever carries about him a piece of this ferruginous pith is invulnerable to any sword or iron whatever.” In Hirnaim de Typho this tree is said to produce fruit impenetrable by iron.