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Pakistan | Family List

Amaranthaceae

C.C. TOWNSEND


Herbarium, Royal Botanic Gardens, Kew.

Bosea amherstiana
Illustration

Credit: M.Y. Saleem

Annual or perennial herbs or subshrubs, rarely scandent. Leaves simple, alternate or opposite, exstipulate, entire or almost so. Inflorescence a dense head, loose or spike-like thyrse, spike, raceme or panicle, basically cymose, bracteate; bracts hyaline to white or coloured, subtending one or more flowers. Flowers hermaphrodite or unisexual (plants dioecious or monoecious), actinomorphic, commonly bibracteolate, frequently in ultimate 3-flowered cymules; lateral flowers of such cymules sometimes modified into scales, spines or hooks. Perianth uniseriate, membranous to firm and finally ± indurate, usually falling with the ripe fruit included, tepals free or somewhat fused below, frequently ± pilose or lanate, green to white or variously coloured. Stamens as many as and opposite to the petals, rarely fewer; filaments free or commonly fused into a cup at the base, alternating with variously shaped pseudo-staminodes or not, sometimes almost completely fused and 5-toothed at the apex with entire or deeply lobed teeth, some occasionally anantherous. Ovary superior, unilocular; ovules 1-many, erect to pendulous, placentation basal; style very short to long and slender; stigmas capitate to long and filiform. Fruit an irregularly rupturing or circumscissile capsule (utricle) usually with thin, membranous walls, rarely crustaceous or a berry. Seeds round to lenticular or ovoid, embryo curved or circular, surrounding the ± copious endosperm.

A large and almost exclusively tropical family of some 65 genera and over 1000 species, including many cosmopolitan “weeds” and a large number of xerophytic plants.

Type genus: Amaranthus L.

In some tropical Floras keys to the Amaranthaceae have been supplied using as primary division the character of opposite or alternate leaves. Of Pakistani genera of this family Deeringia, Celosia, Bosea, Amaranthus and Digera appear to have leaves constantly alternate, and Pupalia, Achyranthes, Alternanthera, Gomphrena and Iresine opposite. Unfortunately, both Aerva sanguinolenta and Nothosaerva brachiata vary with either opposite or alternate leaves and branches.

Acknowledgement: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480.


1 Plant with fertile flowers subtended by modified sterile flowers formed of antler-like scales or hooked spines   (2)
+ Plant with fertile flowers never subtended by modified sterile flowers   (3)
       
2 (1) Leaves alternate; modified sterile flowers represented by antler-like scales   Digera
+ Leaves opposite; modified sterile flowers represented by hooked spines   Pupalia
       
3 (1) Filaments fused almost to the tip. The tube 5-toothed, teeth deeply bilobed with the anthers set between the lobes; bracteoles with a vertical crest along the dorsal surface of the midrib   Gomphrena
+ Filaments fused at the base only; bracteoles not dorsally cristate   (4)
       
4 (3) Ovary with few to many ovules   (5)
+ Ovary uniovulate   (6)
       
5 (4) Fruit a berry; flowers in racemes, the upper forming a large, broad, terminal panicle; tepals 1.5-2.25 mm   Deeringia
+ Fruit a circumscissile capsule; flowers in dense silvery to pinkish spikes; tepals 6-10 mm   Celosia
       
6 (4) Pseudo-staminodes absent   (7)
+ Pseudo-staminodes present   (9)
       
7 (6) Straggling shrub ; fruit a globes berry   Bosea
+ Herbs; fruit a circumscissile or irregularly rupturing capsule   (8)
       
8 (7) Flowers hermaphrodite; stigma solitary, capitate   Nothosaerva
+ Flowers unisexual; stigmas 2-3, linear   Amaranthus
       
9 (6) Flowers in lax panicles, unisexual   Iresine
+ Flowers in spikes or axillary heads, hermaphrodite   (10)
       
10 (9) Bracteoles strongly spinescent with the long-excurrent midrib; flowers in pedunculate spikes, the lower flowers increasingly distant in fruit   Achyranthes
+ Bracteoles mucronate or aristate, but not strongly spinescent; flowers in dense, axillary , sessile or pedunculate heads or spikes   (11)
       
11 (10) Stigma capitate; tepals glabrous of almost so, or with tufts of glochidiate hairs   Alternanthera
+ Stigmas 2, distinct, divergent; tepals ±densely lanate   Aerva

  • List of lower taxa


     

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