Rutaceae. 



Xanthoxylum mauiense Mann. 

 Ae or Heae. 



XANTHOXYLUM MAUIENSE Mann, Proc. Bost. Soc. Nat. Hist, X. (J 866) 319, et Proe. 

 Am. Acad. VII. (1867) 160, et Fl. Haw. Isl. Proc. E9S. Inst. V. (1867) 170;- 

 libd. Fl. Haw. Isl. (1888) 74;— Del Cast. 111. PI. Ins. Mar. Pac. VI. (1890) 130.— 

 Fagara mauiensis Engler in Engl, et Prantl Pflzfam. III. 4. (1895) 119. 



Leaflets 3 on a common petiole of 2.5 to 3 cm, ovate or ovate-oblong 6 to 8 cm long, 

 3.5 to 5 cm wide, acuminate or somewhat obtuse, pale coriaceous, quite oiJaqvie, puberu- 

 lent above, gray-tomentose underneath as well as the petioles and petiolules in the writer's 

 specimens, the lateral ones subtruncate at the base, more or less cut in the upper half, on 

 petiolules of 2 to 4 mm, that of the median leaflet 16 to 18 mm, and often articulate near 

 the blade; panicles 3.5 to 10 cm long many flowered, the common peduncle 2.5 to 4.5 cm, 

 the pedicels about 4 mm, tomentose; follicles 8 to 10 mm, stipitate, lumilate-obovoid, the 

 apex almost lateral, after dehiscence recurved, rugose and pitted. 



This species seems to be indeed a very variable one; the writer has collected 

 material of this species on Maui, Hawaii and Lanai, and even specimens of a 

 small tree were collected by him on Kauai, which seems to be intermediate be- 

 tween X. mauiense and X. hawaiiense ; the petiolules of the lateral leaflets being 

 shorter than in hawaiiense, but longer than in mauiense. The specimens from 

 the above-mentioned islands vary considerably, especially those from Lanai, and 

 from Maui proper. Horace Mann's type came from West Maui, in which 

 latter locality the writer did not find any Xanthoxylum. The specimens on 

 which l\Iann based his species were collected by Eemy n. 615. and Lydgate, but no 

 definite locality is given, other than West Maui. It is the writer's opinion 

 that the tree must be a dry district species, as all other varieties occur in the 

 mixed forests, rather than in mesophytic forests. The writer's specimen which 

 comes closest to the original description came from the lava fields of Puuwaa- 

 waa, North Kona, Hawaii, on the slopes of Mt. Hualalai (no. 3716), where the 

 genus Xanthoxylum has numerous representatives. 



The leaves and inflorescence are quite pubescent, and the former opaque, and 

 as a whole answer well to Mann's description; there seems, however, to be a 

 transition type present which has the pubescent leaves, and besides being tri- 

 foliolate, has also five leaflets, which would remind one of X. Icauaiense. The 

 species is dioecious, a fact of which Hillebrand was not certain. 



Specimens gathered on the Island of Lanai, in Mahana Valley (no. 8112), un- 

 doubtedly will have to be referred to this species, though differing from it in 

 the less coriaceous and perfectly glabrous leaves, and may therefore be called 

 forma glabrum f. nov. liillebrand describes a var. p. from Maunahui, Molokai, 

 which differs from the species in the very long petioles 5 to 10 cm, the leaves of 

 which are glabrous above and coarsely pubescent underneath, with pellucid dots 

 along the margin. The writer is unacquainted with this variety. 



Another variety described by Hillebrand as var. y the writer collected on Lanai. 

 This latter tree is indeed quite common on Lanai, occurring on the main ridges 

 Lanaihale and Haalelepakai ; elevation 3000 feet. It may be described as follows : 



203 



