LON-CAPA Cycas


Cycas macrocarpa	Photo Ken Hill

The Cycad Pages

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 (

indicates that a page has at least one image;

indicates that a page has a complete treatment).

C. angulata
    C. apoa
    C. arenicola
    C. armstrongii
    C. arnhemica
    C. badensis

C. balansae
C. basaltica

C. bougainvilleana

C. brachycantha
C. brunnea

C. calcicola
C. campestris
C. canalis

C. chamberlainii

C. changjiangensis

C. chevalieri
C. circinalis

C. clivicola
C. collina

C. condaoensis
    C. conferta
    C. couttsiana
    C. curranii

C. debaoensis
C. desolata

C. diannanensis

C. dolichophylla

C. elongata
C. falcata

C. ferruginea
C. fugax
C. furfuracea

C. guizhouensis

C. hoabinhensis

C. javana
C. lanepoolei

C. media
C. megacarpa

C. micholitzii
C. micronesica

C. multifrondis

C. multipinnata

C. nongnoochiae
C. ophiolitica
C. orientis

C. panzhihuaensis
C. papuana

C. pectinata
C. platyphylla

C. pranburiensis

C. pruinosa
C. revoluta

C. riuminiana
C. rumphii

C. schumanniana

C. scratchleyana

C. segmentifida
C. semota

C. simplicipinna
C. spherica

C. taitungensis

C. yorkiana
C. yunnanensis

C. zeylanica
There are also several names in wide use that are either invalid or unassignable:
    C. bellefontii
    C. neocaledonica
    C. szechuanensis
    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 parvulus 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 diannanensis -- 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 seemanii 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 Royal Botanic Gardens Sydney
Written and maintained by Ken Hill
Please send comments and corrections