Cojoba mariaelenae L. Rico, Kew Bull. 46: 510, fig. 4F-H. 1991 — "Mexico, Oaxaca, Torres & Martínez 4829" — Holotypus, K!; isotypi, AAU, n.v., BM, n.v., CR, n.v., MEXU (labeled "5 km al NE del Rancho la Gloria, ó 14 km NE de Rizo de Oro, hacia la Col. Rodolfo Figueroa")!, MO!, NY!. In the protologue Rico puts this locality in Oaxaca; rather, it is in Mpio. Cintalapa, Chiapas.

Unarmed trees to 10 m tall, the young stems and lvs densely red-puberulent with incurved-ascending or appressed hairs 0.1—0.4 mm long, the lft-pulvinules, dorsal and sometimes ventral side of lf-axes blond-puberulent, the lvs bicolored dark-green lustrous above, paler beneath, the margins sometimes feebly undulate, the fascicles of sequentially maturing peduncles axillary to coeval leaves or on efoliate nodes of annotinous branches. Stipules deltoid(!), ±1 mm, fugacious, present only at inception of leaves. Lf- formula (ii—)iii-iv/5—12, the somewhat dorsiventrally flattened or more or less terete lf-stalks (3.8-)7.5-14.5 cm, the petiole 2.3-4.5 cm, the interpinnal segments (1.1-) 1.6-3 cm, the petiole charged nearly half-way, or immediately below first pinna-pair (but not in both places) with an elliptic immersed-poriform or round, mounded, or crateriform nectary 0.75-2 mm diam, similar or sessile patelliform nectaries present immediately below each or all but the furthest pinna-pairs;  pinnae, except for the sometimes smaller proximal pair, subequilong, (5.5—)7.5—15 cm, the interfoliolar segments 8-41 mm; lft-pulvinules round or ellipsoid 1-1.5 mm diam on long axis, transversely wrinkled, in dried specimens folding ventrally, lfts appressed against pinna-rachis; lfts elliptic, ovate- or oblong- elliptic from an inequilaterally attenuate base, the terminal pair sometimes falcately so, otherwise not dissimilar, proximally somewhat decrescent, the longer ones at mid-rachis 19-25 x 7-13 mm, 1.9-2.7 times longer than wide, the apex inequilaterally broadly acute or rounded, glabrous save for the ventrally sparingly to moderately blond-puberulent midrib and pulvinus, also sometimes ciliolate; venation pinnate- palmate, the midrib subcentric to forwardly displaced to divide blade ±1:2, secondary and tertiary venation obscure on upper surface, on lower surface with 1-3 posterior veins from pulvinus, the inner one brochi-dodrome well below or beyond half-way up leaflet, the fine tertiary venation subprominulous. Peduncles 1-5 per fascicle, sometimes only one at a time in bloom, the others formed but not developed, more or less subequilong or grossly disparate in length, to 4 cm, charged or not above middle with a thickened bract; capitula 43-54-flowered, the sessile homomorphic 4-5-merous flowers spreading in all directions from a globose or subclavate receptacle 2.25-3.5 mm diam; bracts somewhat dimorphic, the basal ones obovate or obtriangular, ±0.75 mm, distally becoming more linear-spatulate and to 1.25 mm, all somewhat thickened distally and densely red-brown-puberulent, deciduous; perianth 5-merous, externally uniformly pale-brown-puberulent, or red-brown-puberulent only on the calyx- and corolla-lobes; calyx cylindric-campanulate 1-3.5 x 0.75-1.5 mm, ± 4-angulate at base, contracted or not into a pedicel to 0.5 mm long, always broader than long, the unequal, broadly deltate teeth 0.1-0.3 mm; corolla narrowly cylindric-funnelform 6.5-7.5 mm, the ascending lance-ovate lobes 1-1.25 mm, minutely internally cucullate at tip; androecium ±23-44-merous, 10-13 mm, the stemonozone 0.75-1.25 mm, the tube 4.5-8 mm, included in or surpassing the corolla lobes, thickened at base but probably lacking a nectarial disc; ovary subsessile, elliptic, glabrous; style more or less equal to or a little surpassing the stamens, the stigma poriform. Pod (one seen not complete) from reconstruction moniliform ±8 cm long, 1.6 cm broad over seed-cavities, the valves externally red when fresh, when dry evenulose brown and wrinkled, internally brown-lustrous in seed-cavities; seeds seen only broken, ±15-16 mm long, the seed-coat lustrous black. 

In montane wet forest at 1400-2600 m, known only from Sierra Madre de Chiapas, S Chiapas, Mexico. — Map 15. — FI. XI, II-IV, fr. VI.

Cojoba escuintlensis is included in the arborea- clade on the basis of the sequentially maturing unit-inflorescences (Fig. 3, char. 14), and furthermore is sister-group to beckii+chazutensis, with which it shares leaf-nectaries between most if not all leaflet-pairs. It should be noted that two homoplasious characters, namely deltoid stipules (no. 3) and dimorphic bracts (no. 12) are also shared with C. sophorocarpa and C. costaricensis.