Angiosp : Dicot ; Polypet : Thalamifl : Disciflorae — Geraniales. VI. 



DISCIFLORAE ((?«;., Plant. 1862), a convenient assemblage of largely 

 tree-pliyla, characterized by a eucycUc type of floral organization, in which reduction 

 of the androecium to a limit of 3 + 5 in whorled alternation is typically associated 

 with the specialization of a receptacular (//yf-nectary, usually indicating entomophily 

 by the agency of insects with shorl-proboscides (primarily). 



The floral organization thus normally presents a quincuncial calyx, a whorled 

 jientamerous corolla, two whorls of stamens, and a single whorl of 5 carpels : the 

 alternation is not necessarily concurrent throughout the system, and the 5 carpels 

 are typically antipetalous. The gynoecium may reduce to fewer carpels (4, 3, 2), 

 rarely increased by irregularity, and the output of ovules may vary within wide limits. 

 The eucyclic type appears as the symmetrical and complete construction formerly 

 abstracted empirically by older moiphologists as a key to floral evolution. 



The construction may present further specialization for insects of higher grade, 

 as by zygomorphy (median or oblique), or by attempts at tubular organization in 

 calyx or androecium. Reduction may occur in phases of tetramery, irregularity 

 m hexamery, dicliny and dioecism, apetaly, isostemony, and the limitation of gynoecial 

 output, with a single ovule setting a single seed per flower as the end-term. All 

 phases of fruit-elaboration obtain, from many-seeded deliiscent capsules to inde- 

 hiscent berries, nuis, and drupes. The families have been sorted out largely by special 

 features of somatic organization and hy special types of fruit-elaboration. 



In absence of any other very distinctive characters it has become traditional 

 to isolate two empirical series, according to the orientation of the residual ovules 

 in the reduced ovary, as Geraniales (Geranium-type), ovules pendulous with raphe 

 internal, and Sapindales (Horse-Chestnut-type), with raphe external. More herbaceous 

 families (Oxalidaceae, Linaceae, Geraniaceae, Tropaeolaceae, Balsaminaceae) in 

 cuUivation (Hort.) are omitted, and the diclinous Euphorbiaceae are taken in their 

 old position with the apetalous families as a matter of convenience (p. 36). 



Also note, the characteristic disc-nectary {discus) may be intra-staminal. extra- 

 staminal, generally receptacular, or superseded by other mechanism {Pelargoniuvi, 

 Tropaeolum, Impaiiins), and there is no very convincing evidence that many of the 

 families conventionally associated express any actual derivation from the typical 

 eucyclic constiuction after all {Acscu/us, Acer, Tropaeolum), but may represent 

 end-terms of a general convergence to a minimum of working-mechanism of similar 

 jiarls. 



I. Erythi'oxylaceae (2/194) isolated for Erylhroxylon; cf E. coca of 

 S. Amer. Erythroxylon monogynxim a small tree of dry districts, S. India ; leaves, 

 I in., simple ; flowers small, 6 mm., axillary ; pentamerous with 5 -)- 5 stamens 

 united below in a staminal tube, and 3 carpels : Fruit a scarlet drupe, 1 locuhis fertile 

 with I seed. 



II. Malpighiaeeae (54/500) woody shrubs, largely lianoid, based on Mal- 

 pighia of Tropical America : flowers pentamerous, commonly zjgoniorphic, stamens 

 5 + 5. carpels 3. 



Hiptage Madablota, a straggling climbing shrub of forest-ravines : flowers 

 complex, with sternotribal presentation, obliquely zygomorphic in plane of sep. 3 

 (giving odd petal at back), i in. 'diam. ; stamens 10, the fi'ont one larger than the 

 others ; carpels 3 : Fruit an angular nut, i-seeded, with 3 divergent wings, the 

 middle one longer, 2 in. 



III. Rutaceae (i 11/800) a key-group (cf. Ruld) with typically full eucyclic 

 organization, distinguished by oil-glands in the leaves : flowers range to tetramery, 

 with irregularities of construction in Aurantieae-section : cf. — 



Choisya ternata (Hon.), evergreen shrub of Rlts. of Mexico, leaves opposite, 

 3-lobed, glossy and aromatic : terminal corymbose panicles of white flowers, i in. 

 di.im. ; petals 5-8, stamens 10-15; ''le filaments massive, white, making close- 



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