Angiosp : Dicot : I\ronochlamvdeae — Urtic ales. XIII. 



MONOCHLAMYDEAE include groups in which the floral organization is 

 apparently primitively ■ apetalous ', in the sense that the essential floral organs are 

 invested by a simple perianth as one contact-cycle of protective leaf-members. In all 

 cases associated features of extreme reduction prevail in the general construction 

 (dicliny, dimery. trimery), and may be combined with extreme specialization in the 

 gynoecium (dicliny, dimery, syncarpy, inferior ovary, and reduced output of ovules 

 and seeds). Such phenomena suggest that little reliance can be placed on these 

 features a^ indicating primitive nature, and many extreme cases remain so isolated 

 that any serial arrangement is wholly arbitrary. The individual families are usually 

 distinguished by some one dominant character, the exact bearing of which may be 

 wholly vague. A rough distinction may always be drawn between types with simple 

 floral receptacle and those in which epigyny has been attained, and special cases of 

 gynoecium-elaboration may be isolated. 



Urticales (Engler, 1912, = Urticinae, Eichler, 1878), a large section con- 

 veniendy grouped around the familiar Urtica (Sting Nettle) of the N. Temp., and 

 extended to include a vast series of types characterized by advanced flowers (pre- 

 dominantly diclinous and dioecious, apetalous and dimerous) with the gynoecium as 

 the limit of syncarpy (2 carpels), still ' superior ', but containing only i ovule, and 

 setting I -seeded indehiscent fruits. 



I. In the Urtieaceae (41/500) the ovule is typically orthotropous w^ith basal 

 placentation, as the most special case ; few are shrubb}'. Tropical herbaceous 

 Nettles sting badl\- {U. slimulans, U. urcniissima). 



Laportea crenulata, a small tree of Hill-forest, very virulent ; leaves elliptic, 

 may be entire ; flowers small (3 mm.) in loose axillary panicles, all parts with stinging 

 hairs. Giiardinia zeylanica, fibres as textile retain ' stinging ' properties. 



Boehmeria nivea (Ramie, Rhea) of Malay, cult., monoecious, herbaceous and 

 shrubby, cult, for fibre of annual shoots (6-10 ft.), leaves serrate, with drip-tip ; 

 important textile. 



II. Ulmaceae (13/132), based on Ulmus, Elm, with small clusters oi hermaphro- 

 dite flowers, produced in spring before the leaves, of pentamerous type (per. 5, 

 stamens 5, carpels 2), with i ovule suspended, micropyle upward; fruit a winged 

 samara, seed without endosperm : cf. : — 



Ulmus Walliehiana, a large deciduous tree of NW. Himalja (at 1-2 miles 

 elevation) in damp ravines. Flowers in globose clusters, perianth 4 mm. ; samara 

 \ in. diam. with seed centred. 



Holoptelea integrifolia, a large deciduous tree of Sub-Himalya and hill- 

 regions, with entire leaves : flowers hermaphrodite and staminate only, in loose mi.xed 

 racemes: samara i in. diam., on an elongated stalk, i in., no distal notch. 



Celtis australis, deciduous tree of NW. Himalya and S. Europe, cult. ; 

 flowers small, the hermaphrodite solitary or in pairs, axillary: fruit a drupe, fin., red 

 or black, sweet. 



Trema orientalis, a small short-lived tree of NW. Himalya, and cult. ; 

 coming up in clearings of damp forest : flowers mixed in axillary clusters ; Fruit 

 a small black drupe (4 mm.) with persistent per. segs. 



III. Moraceae (.35/900), a tree-series, with latex, the flowers small and 

 aggregated into complex condensed cymose inflorescences which may end in taking 

 on the mechanism for pollination. Individual florets then reduce to extreme limits, 

 but the superior ovary retains two stigmas and one suspended anatropous ovule ; 

 fruits as minute achenes or drupes commonly become united in a succulent 

 aggregated fruit-mass giving pseudocarps of very striking character and of economic 

 value. 



Morus alba, White Mulberry, a deciduous tree of W. and Central Asia, 

 commonly cult. N. India, for silk-industry, and with Sissoo : flowers monoecious, 



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