NEOMAMMILLARIA. 167 
and var. minima Salm-Dyck (Cact. Hort. Dyck 1849. 10. 1850; M. digitalis Ehrenberg, 
Allg. Gartenz. 16: 267. 1848). 
MAMMILLARIA HELICTERES De Candolle, Mém. Mus. Hist. Nat. Paris 17: 31. pl. 5. 1828. 
This name was based on Mocifio and Sessé’s drawing of a Mexican plant, which has 
never since been definitely identified. It was called by them Cactus helicteres (De Candolle, 
Prodr. 3: 460. 1828), but it was renamed Mammnillaria convoluta by St. Lager (Ann. Soc. 
Bot. Lyon 7: 130. 1880). The published drawing indicates that the plant is of this genus. 
MAMMILLARIA HEXACANTHA Salm-Dyck, Hort. Dyck. 344. 1834. 
Cactus hexacanthus Kuntze, Rev. Gen. Pl. 1: 260. 1891. 
Solitary, short-cylindric; tubercles somewhat compressed, light green; areoles ovate to oblong 
when young, white-tomentose, glabrate in age; radial spines 25 to 30, white, 4 mm. long; central 
spines 6, stouter than the radials, brown, the 4 lateral ones 8 mm. long, the uppermost ones a little 
longer, the lowermost ones 18 mm. long, somewhat deflexed; flowers and fruit unknown. 
This plant, which is of Mexican origin, is unknown to us except from description; 
Schumann referred it to Mammillaria coronaria, but it has nothing to do with that plant. 
MAMMILLARIA IRREGULARIS De Candolle, Mém. Mus. Hist. Nat. Paris 17: 111. 1828. 
Cactus irregularis Kuntze, Rev. Gen. Pl. 1: 260. 1891. 
Cespitose, 5 cm. high, with a subtuberous base; joints ovoid, 2.5 cm. in diameter; spines all 
radial, 20 to 25, spreading or somewhat reflexed; flowers and fruit unknown. 
This plant was collected by T. Coulter (No. 31). It has never been re-identified. 
It was grown at the Botanical Garden at Geneva, Switzerland, at the time the description 
was published but, unfortunately, no specimens were preserved; other types based on 
Coulter’s plants are similarly lost and can never be certainly identified. 
MAMMILLARIA JOOSSENSIANA Quehl, Monatsschr. Kakteenk. 18:95. 1908. 
Simple, globose to cylindric, up to 5 cm. high, 3 cm. in diameter, pale green, slightly depressed 
at apex; young areoles white-woolly; radial spines 20, slender-subulate, straight, white, 12 mm. 
long; céntral spines 4, stouter than the radials, 15 mm. long or more, one of them often hooked; 
flowers small, yellow. 
We know this plant, which is a native of Mexico, only from description and two small 
plants sent us by Frantz de Laet in 1922. Quehl places it in Schumann’s classification 
just after M. amoena, although one of the central spines is hooked. 
MAMMILLARIA LESAUNIERI Rebut in Schumann, Gesamtb. Kakteen 533. 1898. 
Simple, globose, or a little longer than broad; tubercles conic, their axils naked ; radial spines 
II to 13, slender, subulate, straight, white, 6 to 8 mm. long; central spines solitary, very short (5 
mm. long or less), brownish, erect; flowers reddish, 2.5 cm. long. 
Type locality: Described from cultivated plants. 
Distribution: Supposed to be Mexico proper or Lower California. 
This species is supposed to have the habit of Mammillaria heydert. 
Here probably belongs Mammillaria lassonneriet Rebut (Monatsschr. Kakteenk. 7: 
29. 1897), a garden name of which we have found no accompanying description. The 
dealer, Grassner, in his Catalogue of Cacti for 1912 (p. 21) and 1914 (p. 33) has illustrated 
M. lassaunieri. 
MAMMILLARIA LEUCOCENTRA Berg, Allg. Gartenz. 8: 130. 1840. 
Cactus leucocentrus Kuntze, Rev. Gen. Pl. 1: 260. 1891. 
Ovoid, about 10 cm. high; tubercles ovoid, their axils very white-woolly; young spine-areoles 
white-tomentose at first, becoming naked; radial spines spreading, numerous, setose, white; central 
spines 4 to 6, stouter and longer than the radials, white throughout or with black. 
Recorded from Oaxaca, but not identified. 
