Rutaceae. 



arrangement are not at all well brought out in the Hawaiian species. In most 

 of the other works Bngler's new combinations have been placed as synonyms. 



The genus Xanthoxylum is distributed over North America, Eastern Asia and 

 also most tropical countries. It is found in Polynesia, outside of the Hawaiian 

 Islands, where seven species and numerous varieties have so far been discovered, 

 only in Tahiti. All Hawaiian species are unarmed. The leaves are quite aro- 

 matic, most of them having a peculiar soapy odor, while one, X. hawaiiense Hbd. 

 var. citriodoro, is strongly lemon-scented. The flowers of some species are also 

 quite fragrant. 



Most of our Xanthoxyla inhabit the dry regions on the leeward sides, espe- 

 cially old lava flows, where they reach their best development, as, for example, 

 on the southern slopes of Mt. Haleakala, Puuwaawaa, North Kona, Hawaii, and 

 on Mauna Kea in the open scrub-country. Several species occur only in the rain 

 forests, as X. oahuense and X. Bluettianum. They are usually found at an ele- 

 vation of 2500 to 4000 feet, but rarely higher. All Hawaiian Xanthoxyla are 

 trees, except a new species found in the Kohala rain forests. 



KEY TO SPECIES. 



Petals 4, thin and slightly imbricate. Flowering panicles appear before the leaves in the 

 axils of large scales. 



Leaflets pedately ternate, the lateral ones on long petiolules. 



All petiolules articulate at or below the middle X. Oahuense 



Lateral petiolules without articulation X. hawaiiense 



Leaflets ovate euneate on petiolules of 16-20 mm X. Bluettianum 



Leaflets 7 to 3 foliolate the lateral leaflets sessile or on short petiolules. 



Leaflets 9-7 lanceolate with copious oil-dots X. glandulosum 



Leaflets 5-3 ovate or ovate oblong opaque X. Kauaiense 



Leaflets 3 or rarely 5, thick, tomentose truncate at the base. . . X. Mauiense 



Petals 4 or 2, thick coriaceous and valvate. Small stipelliform leaflets at the base 



of the lowest leaflets . • X. dipetalum 



Xanthoxylum Oahuense Hbd. 



Ae or Heae. 



(Plate 76.) 



XANTHOXYLUM OAHUENSE Hbd. PI. Haw. Isl. (1888) 75;— Del Cast. HI. PI. Ins. Mar. 



Pae. VI. (1890) 130. — ^Fagara Oahuensis Engler in Engl, et Prantl Pflzfam. III. 



4. (1895) 119. 

 A small tree, glabrous; leaves 3-foliolate, on long petioles of 8 to 10 cm, their leaflets 

 on petioles of nearly even length, the terminal one 5 to 8 cm, the lateral ones 4 to 5 cm, 

 all of which are articulate or thickened in the upper fourth, ovate or orbicular, 7 to 8 

 cm long, 5 to 7 cm or more wide, caudate-acuminate, the lateral ones unsymmetrical at the 

 base, excised in the upper half, glabrous coriaceous, opaque, dark green, brownish-black 

 when dry; panicles at the base of the branch 6 to 12 cm long, loosely and few-flowered; 

 male flowers: sepals minute, petals greenish, ovoid-oblong blunt at the apex, imbricate in 

 the bud, stamens slightly exserted 2.5 mm in length, with subglobose anthers; follicles 10 

 to 12 mm, rugose and pitted. 



The Oahuan A'e or Hea'e is a small, rather handsome tree and is peculiar to 

 the island after which it is named. It is one of the few Hawaiian Xanthoxyla 

 which inhabits the wet middle, or rain forest zone, growing on the highest 



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