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The Cycad Pages
Cycas macrocarpa
Cycas macrocarpa Photo Ken Hill
GENUS  Cycas
K.D. Hill

Cycas L., Sp. Pl.: 1188 (1753); from the Greek Koikas, a kind of palm. Type: C. circinalis L.
The single genus in the family Cycadaceae, Cycas is made up of about 90 species, chiefly Australian (26 species) and Indo-chinese (about 30 species). The genus also occurs in the Malesian region, Japan and South east Asia, extending to Micronesia and Polynesia, Madagascar and East Africa. Four sections are recognised.

Plants are commonly understorey shrubs, sometimes quite large, on well-drained soils in forest, woodland or savanna habitats, often on specific soils or substrates.


Distinguishing characters:

  • Leaves pinnate or rarely bipinnate
  • Leaflets midrib, lacking secondary veins
  • Leaflets not articulated
  • Megasporophylls not gathered in cones

Select a species, or go to the keys to species
Individual species pages will have literature references and synonyms, and eventually images, distribution maps, descriptions and general notes on the species. These are not yet all in place for all species, but the database is slowly growing. On species pages, click on thumbnail images to see full-screen images (Red dot indicates that a page has at least one image; Green dot indicates that a page has a complete treatment). links to images of type specimens held by the New York Botanical Garden (NY) or the National Herbarium of New South Wales (NSW) links to images of the protologue or original description pertaining to the name.

    C. aculeata
    C. aenigma
Green dot C. angulata
    C. apoa
    C. annaikalensis
Red dot C. arenicola
Green dot C. armstrongii
Green dot C. arnhemica
    C. badensis
Green dot C. balansae
Green dot C. basaltica
Red dot C. beddomei
Red dot C. bifida
Red dot C. bougainvilleana
Red dot C. brachycantha
Green dot C. brunnea
Green dot C. cairnsiana
Green dot C. calcicola
    C. campestris
    C. candida
Green dot C. canalis
Red dot C. chamaoensis
Red dot C. changjiangensis
Green dot C. chevalieri
    C. circinalis
Green dot C. clivicola
Red dot C. collina
Red dot C. condaoensis
Green dot C. conferta
Green dot C. couttsiana
    C. curranii
Red dot C. debaoensis
    C. desolata
Red dot C. diannanensis
Green dot C. dolichophylla
Red dot C. edentata
Green dot C. elephantipes
Green dot C. elongata
    C. falcata
Red dot C. ferruginea
Red dot C. fugax
Green dot C. furfuracea
Green dot C. guizhouensis
Green dot C. hainanensis
Red dot C. hoabinhensis
Red dot C. hongheensis
Green dot C. indica
Green dot C. inermis
Red dot C. javana
Red dot C. lacrimans
Green dot C. lanepoolei
Green dot C. lindstromii
Red dot C. maconochiei
Green dot C. macrocarpa
Green dot C. media
Red dot C. megacarpa
Green dot C. micholitzii
    C. micronesica
Red dot C. montana
Red dot C. multipinnata
Red dot C. nathorstii
Red dot C. nitida
Green dot C. nongnoochiae
Green dot C. ophiolitica
Green dot C. orientis
Green dot C. pachypoda
Green dot C. panzhihuaensis
    C. papuana
Red dot C. pectinata
Green dot C. petraea
Green dot C. platyphylla
Green dot C. pranburiensis
Green dot C. pruinosa
    C. revoluta
Red dot C. riuminiana
    C. rumphii
    C. saxatilis
Red dot C. schumanniana
Red dot C. scratchleyana
Green dot C. seemannii
Green dot C. segmentifida
Green dot C. semota
Green dot C. sexseminifera
Green dot C. shanyaensis
Red dot C. siamensis
Red dot C. silvestris
Red dot C. simplicipinna
    C. spherica
Red dot C. sundaica
    C. szechuanensis
Red dot C. taitungensis
Red dot C. taiwaniana
Red dot C. tanqingii
Green dot C. tansachana
Red dot C. thouarsii
Green dot C. tropophylla
Red dot C. tuckeri
Red dot C. vespertilio
Red dot C. wadei
Red dot C. xipholepis
Green dot C. yorkiana
Red dot C. zambalensis
Red dot C. zeylanica
There are also several names in wide use that are either invalid or unassignable:
    C. bellefontii
    C. neocaledonica
    C. tonkinensis
    C. undulata


Genus description:

Habit: dioecious palm like shrubs with aerial or subterranean, pachycaul, cylindrical stems.

Leaves: pinnate or rarely bipinnate, spirally arranged, produced in seasonal growth flushes interspersed with cataphylls, lower leaflets often reduced to spines. Longitudinal ptyxis erect or rarely reflexed, horizontal ptyxis circinate. Leaflets with a single thick midrib and no lateral veins; stomata confined to abaxial surface in most species; individual ptyxis involute. Leaves pubescent, at least when young, with branched or simple transparent hairs.

Microsporophylls: aggregated into determinate male cones and each with a simple sterile apex, which is often produced into an upturned spine. Each microsporophyll bearing numerous microsporangia (pollen sacs) on its abaxial surfaces. Microsporangia opening by slits. Pollen cymbiform, monosulcate.

Megasporophylls: loosely or tightly imbricate, spirally arranged in an indeterminate terminal rosette with the central axis continuing vegetative growth. Ovules two to many (rarely one), marginally inserted on the stipe and directed obliquely outwards (`ascending'). Megasporophyll apically dilated into a pinnatifid, pectinate, toothed or entire lamina in the distal zone beyond the ovule-bearing stipe.

Seeds: subglobular to ellipsoidal, with a yellow, orange or brown fleshy outer sarcotesta, and with or without spongy tissue beneath the inner woody sclerotesta. Endosperm haploid, derived from the female gametophyte. Embryo straight; with 2 cotyledons that are usually united at the tips and a very long, spirally twisted suspensor. Seeds platyspermic; germination cryptocotylar.


IDENTIFICATION KEYS
Try this experimental multiple-entry key based on the DELTA format.
There is also a more traditional dichotomous key lower on the page.
To use this key, start with one or two characters that are clear. To refine a query, use the BACK button of your browser, return to the original query, and gradually add more characters.
Stems (Habit)
Leaves colour
Leaves (gloss)
Leaves (keel)
Number of pinnae
Petiole (length) cm long
Petiole (spines)
Basal pinnae
Median pinnae
Median pinnae (length) mm long
Median pinnae (width) mm wide
Median pinnae (insertion angle)
Median pinnae (width at base)
Median pinnae (spacing)
Median pinnae margins
Midrib (above)
Midrib (below)
Cataphylls
cataphylls
microsporangiate cones
microsporangiate cones
microsporangiate cones cm long
microsporangiate cones cm diam.
microsporophyll lamina
microsporophyll lamina
(sterile apex)
apical spine mm long
megasporophylls cm long
ovules
lamina
(lamina) mm long
(lamina) mm wide
(lamina)
with (lateral spines)
lateral spines mm long
apical spine
apical spine mm long
seeds mm long
sarcotesta
(sarcotesta)
fibrous layer
sclerotesta
spongy layer



Dichotomous keys - Key to the Sections

1 Ovules tomentose -- Section Asiorientales
1* Ovules glabrous
2 Megasporophyll lamina pectinate
3 Male cones rigid, waxy, microsporophyll apices deflexed
4 Sclerotesta not ribbed -- Section Panzhihuaenses
4* Sclerotesta ribbed -- Section Wadeanae
3* Male cones soft, microsporophyll apices not deflexed
5 Microsporophylls flexible, rounded; sarcotesta not fibrous; sclerotesta verrucose -- Section Stangerioides
5* Microsporophylls rigid, acuminate; sarcotesta fibrous; sclerotesta smooth -- Section Indosinenses
2* Megasporophyll lamina not pectinate -- Section Cycas

Key to the Species

1. Section Asiorientales

1 Pinnae revolute -- Cycas revoluta
1* Pinnae flat -- Cycas taitungensis

2. Section Panzhihuanses

China -- Cycas panzhihuaensis

3. Section Wadeanae

1 Pinnae to 6 mm wide; seeds to 40 mm long -- Cycas wadei
1* Pinnae more than 7 mm wide; seeds more than 40 mm long -- Cycas curranii

4. Section Stangerioides

1 Apical megasporophyll spine not strongly differentiated from lateral spines -- Subsection Stangerioides
1* Apical megasporophyll spine much longer and broader than lateral spines -- Subsection Taiwanianae

4.1. Subsection Stangerioides

1 Pinnae simple
2 Microsporophylls finely apiculate
-- Cycas chevalieri
-- Cycas fugax
-- Cycas hoabinhensis
2* Microsporophylls rounded
3 Cataphylls long, rigid -- Cycas diannanensis
3* Cataphylls short, soft
4 Male cones small, narrow
5 Thailand -- Cycas simplicipinna
5* Vietnam
-- Cycas brachycantha
-- Cycas balansae
4* Male cones large
8 China
-- Cycas yunnanensis
-- Cycas segmentifida
-- Cycas guizhouensis
8* Vietnam
-- Cycas collina
-- Cycas dolichophylla
1* Pinnae dichotomously divided
2 Pinnae 2-3 times dichotomously divided
-- Cycas micholitzii
-- Cycas multifrondis
2* Pinnae pinnately divided and more than 3 times dichotomously divided
-- Cycas multipinnata
-- Cycas debaoensis
4.2. Subsection Taiwanianae

1 Pinnae to 10 mm wide
2 Seeds large -- Cycas hainanensis
2* Seeds small
3 Plants large
4 Leaves keeled -- Cycas tropophylla
4* Leaves flat -- Cycas ferruginea
3* Plants dwarf
5 Hainan -- Cycas changjiangensis
5* Vietnam, Guangxi -- Cycas miquelii
1* Pinnae more than 11 mm wide
5 China
-- Cycas taiwaniana
-- Cycas tanqingii
5. Section Indosinenses

1 Stem wholly subterranean; male cones less than 5 cm diam. -- Subsection Lindstromienses
1 Stem becoming aerial; male cones more than 5 cm diam.
2 Leaves distinctly keeled, tomentose throughout; cataphylls spinescent -- Subsection Hongheenses
2 Leaves flat or moderately keeled, glabrous at least above; cataphylls not spinescent -- Subsection Indosinenses

5.1. Subsection Indosinenses

1 Phelloderm (bark) smooth
2 Male cones fusiform -- Cycas chamaoensis
2* Male cones ellipsoid to ovoid
3 Apical microsporophyll spine long -- Cycas pectinata
3* Apical microsporophyll spine short
4 Male cones large -- Cycas tansachana
4* Male cones small -- Cycas clivicola
-- Cycas elongata
1* Phelloderm (bark) corky
5 Basal pinnae not reducing to spines
6 Male cones medium
7 Vietnam -- Cycas condaoensis
7* Vietnam -- Cycas pachypoda
6* Male cones small -- Cycas nongnoochiae
5* Basal pinnae reducing to spines -- Cycas siamensis

5.2. Subsection Hongehenses

China -- Cycas hongheensis

5.3. Subsection Lindstromiae

Vietnam -- Cycas lindstromii

6. Section Cycas

1 Spongy tissue not present in seeds
2 Fibrous layer present in sarcotesta -- Subsection Cycas
2* Fibrous layer not present in sarcotesta -- Subsection Endemicae
1* Spongy tissue present in seeds -- Subsection Rumphiae

6.1. Subsection Cycas

1* Pinnae less than 5 mm wide -- Cycas beddomei
1 Pinnae more than 6 mm wide
2 Pinnae less than 10 mm wide
3 Lateral megasporophyll teeth less than 3 mm long
4 India -- Cycas circinalis
4 Sri Lanka -- Cycas nathorstii
3* Lateral megasporophyll teeth more than 4 mm long
5 Lateral spines of megasporophyll lamina less than 10 mm long
6 India -- Cycas spherica
6* Philippines -- Cycas riuminiana
5* Lateral spines of megasporophyll lamina more than 10 mm long -- Cycas chamberlainii
2 Pinnae more than 10 mm wide
7 Petiole unarmed -- Cycas pranburiensis
7* Petiole spinescent
8 Lateral megasporophyll teeth more than 8 mm long -- Cycas macrocarpa
8* Lateral megasporophyll teeth less than 7 mm long
9 Lamina distinctly toothed
10 Lamina ovate
11 Vietnam -- Cycas inermis
11* PNG -- Cycas scratchleyana
10* Lamina slender, lanceolate -- Cycas javana
9* Lamina, lacking distinct lateral spines -- Cycas apoa

6.2. Subsection Rumphiae

1 Seeds without a distinct apical wing
2 Pinnae broad, very glossy, bright green
3 Philippines -- Cycas edentata
3* Thailand -- Cycas litoralis
2* Pinnae medium, semiglossy, bluish when new
4 Cataphylls numerous, narrow, elongate; Sri Lanka & Andamans -- Cycas zeylanica
4* Cataphylls fewer, short and broad; Madagascar -- Cycas thouarsii
1* Seeds with a distinct apical wing
5 Lateral megasporophyll spines reduced to bumps -- Cycas rumphii
5* Lateral megasporophyll spines distinct
6 Apical spine more than 15 mm long
7 Pinnae more than 13 mm wide; petiole often spinescent -- Cycas bougainvilleana
7* Pinnae less than 12 mm wide
8 Petiole rarely spinescent -- Cycas seemannii
8* Petiole usually spinescent -- Cycas falcata
6* Apical spine less than 12 mm long -- Cycas micronesica

6.3. Subsection Endemicae

1 Basal pinnae gradually reducing in size
2 Basal pinnae reducing to spines; lateral megasporophyll teeth large, not pungent -- Series Furfuraceosae
2* Basal pinnae not reducing to spines; lateral megasporophyll teeth small, pungent -- Series Calcicolosae
1* Basal pinnae not gradually reducing in size
4 Hypodermis absent; leaf margins flat -- Series Armstrongianosae
4* Hypodermis present; leaf margins recurved
5 Hypodermis interrupted; leaves green
6 Cataphylls strongly spinescent -- Series Endemicosae
6* Cataphylls soft, not spinescent -- Series Yorkianosae
5* Hypodermis continuous; leaves grey or blue
7 Leaves strongly glaucous; male cones small to medium, ovoid -- Series Cairnsianosae
7* Leaves not strongly glaucous ; male cones large, subglobose -- Series Angulatosae

6.3.1. Series Endemicae

1 Leaves keeled at up to 135 -- Cycas megacarpa
1* Leaves flat (keeled at more than 135 )
2 Pinnae > 9 mm wide; cataphylls deciduous -- Cycas silvestris
2* Pinnae < 9 mm wide; cataphylls persistent -- Cycas media

6.3.2. Series Yorkianosae

1 Crown and cataphylls densely orange-woolly or floccose
3 Lateral spines of megasporophyll lamina more than 8 mm long -- Cycas campestris
3*
4 -- Cycas schumanniana
4*
5 Megasporophyll apex 60--100 mm long, with 24--32 lateral spines 3--6 mm long, apical spine 2--16 mm long -- Cycas yorkiana
5* Megasporophyll apex 50--55 mm long, with 22--24 lateral spines 1--4 mm long, apical spine 21--25 mm long -- Cycas badensis
1* Crown and cataphylls very shortly grey to white-sericose
6 Megasporophylls short (10–15 cm); apex dilated (35–50 mm wide) -- Cycas tuckeri
6* Megasporophylls longer (18–25 cm); apex not dilated (18–35 mm wide) -- Cycas semota

6.3.3. Series Cairnsianosae

1 Margins of pinnae revolute; pinnae narrow (mostly less than 4 mm wide)
2 Cataphylls short, soft -- Cycas cairnsiana
2* Cataphylls long, pungent -- Cycas desolata
1* Margins of pinnae flat or recurved, not revolute; pinnae more than 4 mm wide
3 New growth with mainly white or grey trichomes -- Cycas couttsiana
3* New growth with mostly brown or orange trichomes
4 Pinnae 6.0–7.5 mm wide; leaves keeled at 80–120 -- Cycas ophiolitica
4* Pinnae 4.6–6.0 mm wide; leaves keeled at 45–60 -- Cycas platyphylla

6.3.4. Series Angulatosae

1* Pinnae > 6 mm wide -- Cycas brunnea
1 Pinnae < 6 mm wide -- Cycas angulata

6.3.5. Series Armstrongianosae

1 New leaves green or bluish-green
2 Pinnae concolorous, partly amphistomatic, closely crowded and overlapping -- Cycas conferta
2* Pinnae more or less discolorous, hypostomatic, well-spaced on rachis
3 Cataphylls shortly pale brown-tomentose
4 Midrib more prominent below than above -- Cycas orientis
4* Midrib equally prominent above and below
5 -- Cycas xipholepis
5* -- Cycas papuana
3* Cataphylls densely orange-woolly or floccose
6 Stem more than 12 cm diam. -- Cycas lane-poolei
6* Stem less than 12 cm diam. -- Cycas armstrongii
1* New leaves glaucous blue -- Cycas canalis

6.3.6 Series Calcicolosae

1 Margins of pinnae flat or recurved; pinnae broad (more than 5 mm wide)
2 New growth with mostly brown or orange trichomes -- Cycas arnhemica
2* New growth with mainly white or grey trichomes -- Cycas maconochiei
1* Margins of pinnae revolute; pinnae narrow (less than4 mm wide)
3 Pinnae numerous (210-410), narrow (2.5-4.0 mm wide); crowded (spaced at 4-6 mm on rhachis) -- Cycas calcicola
3* Pinnae not as numerous (180-270), wider (4.0-6.5 mm wide); not crowded (spaced at 8-14 mm on rhachis) -- Cycas arenicola

6.3.7. Series Furfuraceosae

1 Leaves flat -- Cycas basaltica
1* Leaves keeled
2 Margins of pinnae revolute; pinnae narrow (less than 4 mm wide) -- Cycas pruinosa
2* Margins of pinnae flat or recurved; pinnae broad (more than 5 mm wide) -- Cycas furfuracea



The Cycad Pages

© 1998-2012 Royal Botanic Gardens Sydney
Written and maintained by Ken Hill 1998-2010
Maintained by Leonie Stanberg and Dennis Stevenson 2010-2012
This site is currently not being maintained