682 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



101. APOCYNACEAE. Dogbane family 



Plants perennial, herbaceous or slightly woody at base, commonly 

 with acrid milky juice; leaves simple, entire, opposite or alternate; 

 flowers perfect, regular, 5-merous; stamens attached separately to the 

 corolla; pistils 2, the ovaries separate, superior, the styles or the stig- 

 mas united; fruit a pair of elongate follicles; seeds often with coma. 



This mainly tropical family comprises many handsome plants, 

 including the well-known oleander (Nerium oleander L.). Not a few 

 of the Apocynaceae are poisonous. 



Key to the genera 



1. Anthers not produced at base, free from the stigma; leaves all, or mostly, 



alternate; corolla normally blue or bright yellow; seeds naked, or comose 



at both ends (2). 



2. Corolla not constricted at the throat, bright yellow, the lobes longer than 



the tube; seeds with coma at both ends 1. Haplophyton. 



2. Corolla constricted at or near the throat, blue (exceptionally whitish), the 



lobes shorter than the tube ; seeds naked 2. Amsonia. 



1. Anthers produced basally into a sterile appendage below the polliniferous 

 portion, connivent around and more or less adherent to the stigma; leaves 

 opposite; corolla whitish or pink; seeds with apical coma (3). 



3. Flowers few, large and showy; corolla salverform, with a long tube and a 



long throat; stamens inserted in the throat of the corolla; ovary superior. 



3. Macrosiphonia. 

 3. Flowers numerous, small; corolla campanulate, cylindric, or urceolate; 

 stamens inserted near the base of the corolla ; ovary partly inferior. 



4. Apocynum. 



1. HAPLOPHYTON. Cockroach-plant, hierba-de-la-cucaracha 



Stems branched, woody below; leaves mostly alternate, bright 

 green, the blades lanceolate or lance-ovate; flowers showy, terminal, 

 solitary or in clusters of 2 or 3, the corolla bright yellow, salverform, 

 with broad lobes longer than the tube; follicles slender, terete; seeds 

 long, slender, black, with a pappuslike, deciduous tuft of long white 

 hairs at each end. 



Superficially, this plant somewhat resembles Menodora. An extract 

 of the dried leaves, mixed with molasses, is an effective poison for 

 insects such as cockroaches, flies, mosquitoes, fleas, and lice. 



1. Haplophyton cimicidum A. DC. in DC, Prodr. 8: 412. 1844. 



Pinal and Pima Counties, 2,500 to 4,500 feet, rocky slopes and 

 canyons, July to September. Southern Arizona and Mexico. 



2. AMSONIA™ 



• 



Plants herbaceous; stems leafy, commonly erect, often numerous 

 from 1 root; leaves alternate or appearing whorled, sessile or short- 

 petioled; flowers in terminal cymose panicles; corolla salverform, pale 

 blue or whitish; seeds numerous, in one series, cylindric. 



The Arizona specie's grow in the open or among shrubs, often along 

 streams and washes, preferring sandy soil. 



i° Reference: Woodson, Robert E., Jr. studies in the apocynaceae. III. a monograph of the 

 genus amsonia. Mo. Bot. Gard. Ann. 15: 379-434. 1928. 



