Rutaceae. 



To the variety anceps must be referred another tree found in the same locality. 

 The inflorescence is exactly as in the variety, but the leaves, which are also 

 pubescent, have three but rarely five leaflets which are subcordate to truncate 

 at the base ; the lateral ones instead of being sessile are on petiolules of about 10 

 mm and are subcordate to unevensided; the leaflets remind one very much of 

 those of Pterotropia Kauaiensis. The terminal leaflet is also articulate. Evi- 

 dently the length of the petiolules of the lateral leaflets, on which Hillebrand laid 

 so much stress, is not a good specific character. According to his key to the 

 species, this latter form, which may be known now as forma petiolulatum f. n., 

 would belong to X. hawaiiense, rather than to X. mauiense, but can not be sep- 

 arated from the latter, as it differs otherwise very materially from the former 

 species, whose lateral leaflets are practically deltoid, with petiolules as long as 

 the terminal one. These varieties and forms seem to be intermediates between 

 X. mauiense and X. hawaiiense, though reminding one much more of the former 

 than of the latter. 



Xanthoxylum dipetalum Mann. 



XANTHOXYLUM DIPETALUM Mann in Proc. Bost. Soc. Nat. Hist. X. (1867) 160 et 

 Proc. Ess. Inst. V. (1868) 170;— Hbd. PI. Haw. Isl. (1888) 76;— Del Cast. HI. PI. 

 Ins. Mar. Pac. VI. (1890) 129. — Fagara dipetala Engl, in 'Engl, et Prantl Pflzfam. 

 III. 4. (1895) 119. 

 Leaves 15 to 18 cm long including a petiole of 2.5 to 3.5 em, pinnately 5 to 7 folio- 

 late, the lowest pair of leaflets generally with a pair of stipelliform or auricular folioles 

 close to its base; lateral petiolules 6 mm, the terminal one 12 to 18 mm, often articulate; 

 leaflets oblong 7.5 to 8.75 cm long, 3.75 to 4.5 cm wide, obtuse, all contracting and nearly 

 symmetrical at the base, coriaceous, with faint nerves and many pellucid dots, glossy; 

 panicles terminal and oppositifolious, 7.5 to 10 cm long, with a peduncle of 2.5 to 3.75 cm 

 and subereet branches, the ternate flowers on pedicels of 6 mm, the lateral pedicels 

 minutely bracteate below the middle; male flowers: sepals 4, rounded, little more than 

 1 mm high; petals 2, lanceolate, thick coriaceous and valvate, 10 mm long, stamens 4, 

 scarcely half the length of the petals, placed on the edge of the disc, with long apicul.ite 

 anthers of 2 to 3 mm; ovary rudimentary. 



This very interesting species, which is quite distinct from all the other Ha- 

 waiian Xanthoxyla, was first collected by Dr. Wm. Hillebrand and communicated 

 by him to H. Mann, who described it. The writer is only acquainted with sev- 

 eral forms or varieties of this species found on the other islands, but has never 

 collected the species proper, found on Oahu by Hillebrand on the slopes of 

 Waiolani, also called Lanihuli, in Nuuanu Valley. The dipetalous flowers occur 

 in the species, and in the varieties the flowers are tetramerous. It is a tree about 

 30 feet high and quite glabrous. In regard to the dipetalous flowers liillebrand 

 quite correctly states: "The reduced number of the petals in the species is 

 owing not to a suppression of a pair, but to coalescence of two contiguous petals ; 

 it is not so much therefore on the strength of these characters that the present 

 species must claim a place distinct from the preceding ones within the genus, as 

 for its mode of inflorescence and the presence of the supplementary pair of 

 reduced leaflets in such an extraordinary position, where they appear like ap- 

 pendages of the lowest folioles. ' ' 



207 



