Sapindales.] 



ACERACE^. 



387 



Order CXXXVIII. ACERACE.E.— Maples. 



Acera, Juss. Gen. 50. (1789) ; Ann. Mus. 18. 477. (1811).— Acerineae, DC. TMorie, ed. 2. 244. (1819^ ; 

 Prodr. 1. 593. (1824) ; Endl. Gen. ccxxvii. ; Meisner, Gen. p. 56. 



Diagnosis. — Sapindal Exogens, loith complete unsymmetrical flowers, petals naked or 0, 

 anthers opening longitudinally , 2 carpels, and seeds without an anl. 

 Trees. Leaves opposite, simple, usually with palmate veins, rarely pinnate, without 



stipules. Flowers often polygamous, in axil- 

 lary corj-mbs or racemes. Calyx divided 

 into 5, or occasionally from 4 to 9 parts, 

 vni\\ an imbricated aestivation. Petals equal 

 in number to the lobes of the calyx, imbri- 

 cated, inserted round an hypogynous disk, or 

 0. Stamens inserted upon the disk, gene- 

 rally 8, not often any other number, always 

 definite. Ovary free, 2-lobed ; style 1 ; 

 stigmas 2 ; ovules in pau's, amphitropal, pen- 

 dulous. Fruit formed of two nuts, which are 

 indehiscent, with a narrow -wdng at the back 

 (samaroid) ; each 1 -celled, \n\h 1 or 2 seeds. 

 Seeds ascending, with a thickened hning to 

 the testa ; albumen none ; embryo curved, 

 with foliaceous wTinkled cotyledons, and an 

 inferior radicle. 



These plants differ from Soapworts in their 

 fruit ha\ing but 2 carpels, the petals never 

 being furnished with scales, and their oppo- 

 site leaves. The distinction is however 

 scarcely satisfactory, even when the want 

 of an aril is added. From Malpighiads 

 their unsjinmetrical flowers, inferior radicle, 

 glandless calyx and palmate-veined leaves, 

 decidedly divide them. 



Europe, the temperate parts of Asia, the 

 north of India, and North America, are the 

 stations of tliis Order, which is imknown in 

 Africa and the southern hemisphere. 

 The species are only kno^vn for the sugary sap of Acer sacchainnum and others, from 



which sugar is extracted in abundance, and for then* light useful timber. ^ It is said, 



however, that their juices become acrid as the season advances. The bark is astringent, 



and yields the dyer reddish brown and yellow colom's. 



GENERA. 



Acer, Linn. 

 Negundo, Monch. 

 Negundium, Raf. 

 Hamilt, 



Fig. CCLXX. 



Numbers. Gen. 3. Sp. 60. 

 Position. — Petiveriaceae. — Acerace^. — Sapindacese. 



Fig. CCLXX.— 1, Acer chcmainra.— Hooker. 2. flower of A. campestre, Gartner; 3. its samara ; 

 4. the same, with the seed laid barej 6. the embrj'O unfolded. 



