STANDLEY ALLTONIACEAE OF MEXICO. 379 



listed as occurring within our limits. In the present paper, owing 

 chiefly to the more extensive exploration of the area, this number 

 has been increased to 113. Hemsley listed 14 genera, while here 

 the number given is 22, this principally due to a different conception 

 of generic limits but partly because of more abundant material. 



SYSTEMATIC TREATMENT. 



ALLIONIACEAE Reichenb. Consp. Veg. 85. 1828. 



Nyctaginaceae Lindl. Nat. Syst. ed. 2. 213. 1836. 



Dr. Anton Heimerl a has proposed the following division of the Allioniaceae into 

 groups. His treatment is most satisfactory, and since it gives one a good general view 

 of the family it is reproduced here. 



I. Pisoniae Heimerl. Embryo straight, the cotyledons slightly recurved; flowers 

 unisexual or hermaphrodite, usually with evident remains of the organs of the aborted 

 sex; perianth usually not differentiated into two parts, that of the pistillate flowers 

 closing at the summit and enveloping the fruit or adhering to its summit. Shrubs or 

 trees, often armed with thorns; leaves opposite.— Neea, Torrubia, Pisoniella, Pisonia. 



II. Boldoeab Heimerl. Embryo strongly curved; flowers hermaphrodite; peri- 

 anth inconspicuous, green, persisting scarcely changed in fruit, not differentiated into 

 a distinct upper and lower part. Plants not armed with thorns, herbaceous, or suffru- 

 tescent at the base; leaves alternate.— Salpianthus. 



III. Mirabileae Heimerl. Embryo strongly curved; flowers hermaphrodite; 

 perianth corolla-like and showy, enlarged and enveloping the fruit, or more or less 

 evidently differentiated into two parts, the lower of which adheres to and envelops 

 the fruit, the other deciduous from or persistent upon its summit. Herbs; leaves 



usually opposite. 



A. Colignoniinae Heimerl. Perianth not adhering to the wall of the fruit, but 

 enlarged and enveloping it at maturity, of like consistency throughout, finally pear- 

 shaped, closed above; fruit without mucilaginous glands; anther cells almost spherical; 

 cotyledons nearly alike; embryo spherical. Herbs with opposite leaves.— Colicnonia. 



B. Bougainvilleinae Heimerl. Perianth not adhering to the wall of the fruit, 

 but enlarged and enveloping it at maturity, of the same thick consistency throughout, 

 the lower part enlarging and enveloping the fruit, the upper drying and adhering to 

 its summit; anther cells spherical to reniform; cotyledons more or less dissimilar but 

 neither abortive; embryo linear-oblong; fruit adnate to the bracts and falling with 

 them. Thorny, woody vines with alternate leaves.— Bougainvillea. 



C. Abronhnae Heimerl. Perianth evidently differentiated into two parts of dif- 

 ferent consistency, the upper part thin, salverform, deciduous, the lower thick, 

 enlarging and forming wings or ribs which adhere to the fruit, without mucilaginous 

 gland's; stigma linear; anther cells oblong; embryo oblong or ellipsoidal, the inner 

 cotyledon abortive. Herbs with opposite leaves.— Tripterocalyx, Abronia. 



D. Boerhaaviinae Heimerl. Perianth evidently differentiated into two parts of 

 different consistency, the upper part thin, deciduous, the lower thick, enlarging and 

 persisting as a coat of the anthocarp, often containing mucilaginous glands; stigma 

 spherical or hemispherical; anther cells almost spherical; embryo spherical, ellip- 

 soidal, or obovoid, the inner cotyledon not abortive. Herbs with opposite leaves — 

 Okenia, Selinocarpus, Wedeliella, Nyctaginia, Allionia, Quamoclidion, Hesperonia, 

 Mirabilis, Acleisanthes, Boerhaavia, Cyphomens, Commicarpus, Anulocaulis. 



ajahresb. Oberrealsch. Fiinfhaus 23: repr. 15-17. 1897. 



