Identification of Costus Species
Dave Skinner
1 Dr. P. J. M. Maas University of Utrecht
Flora Neotropica • Monograph No. 8 – 1972 • Monograph No. 18 – 1977 – updated key Notes on Asiatic Costoideae – 1979 Notes on New World Zing. – 1990 • With wife, Dr. Hiltje Maas – 3 new species described Two New Costa Rican Species – 1997 • P.J.M. & Hiltje Maas
2 Other References
Flore Du Gabon – Jean Koechlin - 1964 • African species (20 species described) • Written in French, includes key Flora of Australia – Rosemary Smith – 1987 Dr. Chelsea D. Specht • Molecular Phylogeny of Costaceae - 2001 • Post-doctoral work at the Smithsonian • Soon-to-be-published Reclassification of Costus
3 Family Costaceae Currently 4 genera
Costus Monocostus Dimerocostus Tapeinochilos
70 species 1 species 2 (4) species 18 species Americas South Central and New Guinea Africa America South Indonesia Asia America Australia Australia
4 Genus Costus 5 subgenera
Eucostus Cadalvena Paracostus Epicostus Metacostus (Costus) Examples Examples Examples Examples Examples C. barbatus C. cuspidatus C. paradoxus C. tappenbeckianus C. lateriflorus C. speciosus C. subsessilis C. englerianus C. arabicus C. curcumoides C. globosus C. lanceolatus C. spicatus C. pictus C. dubius 5
New World Costus Identification Keys by Maas Identification Hierarchy I. Subgenus – (Cadalvena vs. Eucostus) Subgenus Eucostus (Costus) II a. Labellum – spreading (Section I, Melittophilus – Costus) vs. tubular (Section II, Ornithophilus) II b. Bracts – appendaged (Group I) vs. not appendaged (Group II)
6 Example of tubular flowers
Section Ornithophilus
7 Example of spreading labellums
Section Melittophilus
8 Example of appendaged bracts
Group I
9 Example of non- appendaged bracts
Group II
10 Bract Color
11 Bract Margins
12 # of Flowers per Bract
13 Calyx Length
14 Bracteole Shape and Length
15 Ligule Length & Lobes
16 Terminal vs. Basal Bloomers
17 African Costus Identification Keys by Koechlin Identification Hierarchy I. Stems - Stemless (C. spectabilis) vs. upright or creeping II. Leaves - Single leaf (C. englerianus) vs. many leaves III. Inflorescence - Radical (basal) vs. Lateral vs. Terminal IV. Height (basal bloomers) – over 1 meter vs. under 1 meter IV. Appendages (terminal bloomers) – with or without V. Other characters 1. Ligules 2. Single flower vs. two flowers per bract 3. Raised ring on ligule
18 Generally NOT used for identification
Presence of hairs (“fuzziness”) on leaves and pseudostems Coloration of leaves Shape of leaves
19 Costus that have been incorrectly identified in US horticulture
20 21 Costus lacerus Often incorrectly identified as Costus speciosus
22 Costus lacerus Has fibrous margins and blunt ends to the bracts.
23 Costus speciosus Pungent bracts, margins entire 24 25 26 Costus productus Sold in horticulture as Costus curvibracteatus
27 Bracts are appendaged
Costus productus 28 Edge of bract appendage is curved inwards on this plant.
Description of C. curvibracteatus has the apex of the bracts “slightly curved outwards”.
29 Costus productus - ligules 30 Costus ‘Maroon Chalice’ is a form of Costus productus 31 32 Costus scaber Sold in horticulture as Costus spicatus
33 34 Comparison of Costus spicatus (hort.) with Costus scaber (Smithsonian specimen) – the flower parts were identical and matched Maas’ description of Costus scaber.
35 Costus cylindricus (syn. spicatus) As identified at the Smithsonian, #2002-127 36 37 Costus arabicus ‘variegatus’
Sold in horticulture as Costus amazonicus ‘variegatus’ 38 C. arabicus = snow white flowers, tinged purple.
C. amazonicus = yellow corolla, yellow labellum, dark red-striped lateral lobes, yellow with red margined middle lobe, Costus amazonicus Costus arabicus reddish stamen ‘Variegatus’ Specimen from (horticulture) Smithsonian
39 Branching Stems 40 Cordate leaf base
41 New and/or unidentified Costus species
42 Probably a natural hybrid of Costus spiralis X Costus arabicus
43 Costus ‘Tropicais’
44 Costus ‘El Whiskey’ 45 Costus ‘El Whiskey’ 46 Possibly Costus jururanus
47 Some other Costus species
48 Costus allenii ‘Santa Fe form’
49 Costus barbatus 50 Costus chartaceus 51 Costus claviger 52 Costus comosus
53 Costus cuspidatus 54 Costus dubius
55 Costus erythrophyllus 56 Costus erythrothyrsus 57 Costus globosus
58 Costus laevis
59 Costus lasius
60 Costus lucanusianus 61 Costus lucanusianus (yellow form) 62 Costus maculatus
64 Costus mosaicus
65 Costus osae 66 Costus pictus
67 Costus pulverulentus
68 Costus speciosus ‘Variegatus 69 Costus spiralis
70 Costus stenophilus 71 Costus subsessillis 72 Costus talbotii 73 Costus tappenbeckianus 74 Costus varzearum
75 Costus villisissimus 76 Costus vinosus 77 Costus woodsonii
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Thanks – Dave Skinner
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