120 



KEY TO THE FAMILIES AND GENERA 



178. GNETACEjE. 



Leafless shrubs with jointed branches and scales 



opposite the nodes connate into a little sheath. . Ephedra. 



The very curious genus Welwitschia may be found in botanical 

 collections. 



179. TAXACE.E. 



A. Anthers 2-celled: tropical or subtropical trees 



and shrubs. 



B. Scales of pistillate aments few, adnate to 

 peduncle and with it usually fleshy: Ivs. 



linear to ovate, rarely scale-like 1. Podocarpus. 



BB. Scales of pistillate aments short, broad and 

 somewhat fleshy, imbricate: Ivs. minute 

 and scale-like: branchlets flattened and 



If.-like 2. Phulloc- 



AA. Anthers 3-8-celled: Ivs. linear: hardy or nearly [Indus. 



hardy trees and shrubs. 



B. Pistillate fls. consisting of several decussate 

 2-ovuled carpicles: Ivs. with 2 glaucous 

 lines below broader than the 3 green 



lines 3. Cephalo- 



BB. Pistillate fls. reduced to 1 ovule. [lazus. 



c. Carpicles at maturity inclosing the seed 

 and adnate to it: anthers 4-celled, cells 

 free: Ivs. with 2 glaucous lines below 



narrower than the green lines 4. Torreya. 



CC. Carpicles at maturity partly inclosing the 

 seed, not adnate to it: anthers 6-8- 

 celled, cells connate: Ivs. pale green 

 below 5. Taxus. 



180. PINACE.E. 



A. Lvs. spirally arranged. 

 B. Carpicles simple; ovule 1, reversed; 



cone-scales with 1 seed 1. AHAUCAHIA TRIBE. 



BB. Carpicles divided into scale and 



bract, sometimes connate. 

 C. Ovules 2, reversed ; scale and bract 

 always distinct; cone-scales with 



2 usually winged seeds 2. ABIES TRIBE. 



CO. Ovules 2-8, axillary and upright or 

 on the scale and at least finally 

 reversed; cone-scales with 2-8 



seeds 3, TAXODIOM TRIBE. 



AA. Lvs. opposite or whorled, often scale- 

 like: ovules upright 4. CUPRESSCS TRIBE. 



1. Araucaria Tribe. 



A. Seeds free from the scale, with 1 or 2 wings: 

 Ivs. broad, generally elliptic, more or less 



distichous and rather remote 1. Agathia. 



AA. Seeds adnate to the winged or wingless scale: 

 Ivs. large, scale-like or needle-shaped, 

 spirally arranged, crowded 2. Araucaria. 



2. Abies Tribe. 



A. Foliage deciduous, partly fascicled. 

 B. Male fls. solitary in a leafless scaly bud; con- 

 nective not produced beyond anther-cells 

 nor scarcely prominent: cones reflexed; 



scales persistent 3. Larix. 



BB. Male fls. clustered, pendulous: cone-scales 



deciduous 4. Paeudolarix. 



AA. Foliage evergreen. 



B. Connective of anthers usually produced into 



a scale-like appendage, 

 c. Male fls. subspicate at base of new shoots: 

 cone-scales persistent: Ivs. in clusters of 



2-5, rarely solitary 5. Pinus. 



cc. Male fls. solitary in the cluster of Ivs. 

 which terminate short branchlets: cone- 

 scales finally deciduous : Ivs. partly fas- 

 cicled as in the larch 6. Cedna. 



ccc. Male fls. solitary in the axils: cones 

 reflexed; scales persistent: Ivs. solitary, 

 4-angled or flattened and glaucous 



above, green on the back 7. Picea. 



BB. Connective of anthers simply umbonate 



beyond the cells or hardly prominent; 



male fls. solitary in axils: Ivs. solitary, 



usually flattened, glaucous or paler below. 



c. Cones reflexed ; scales persistent. 



D. Subtending bract conspicuous 8. Paeudotauga. 



DD. Subtending bract small 9. Tango. 



CC. Cones erect. 



D. Scales peristent; seeds about as long as 

 scales; bracts much shorter than 

 scales: Ivs. flattened, keeled above, 

 pale below 10. Kettleeria. 



DD. Scales deciduous; seeds shorter than 

 scales; bracts shorter or longer: Ivs. 

 flattened and grooved above, usually 

 glaucous below.rarely 4-angled 11. Abies. 



3. Taxodium Tribe. 



A. Lvs. connate into pairs, arranged in whorls: 

 ovule-bearing blade finally much increased 

 and hardened, making the greater part of the 



woody cone 12. Sciadopit V s. 



AA. Lvs. solitary, scattered. 

 B. Scales of cone flat. 



c. Carpicles entire at apex: anther-cells 2-4: 

 seeds surrounded by a narrow wing: Ivs. 

 lanceolate flat, rather large, glaucous 



_ below 13. Cunning- 



cc. Carpicles toothed at the apex: anther-cells [hamia. 



4-5: seeds 2-3-angled: Ivs. awl-shaped, 



curved 14. Cryptomeria. 



BB. Scales peltate. 



c. Seeds usually 5, narrowly winged: Ivs. 



scale-like or linear, persistent 15. Sequoia. 



cc. Seeds 2, angular: Ivs. linear, deciduous 



with the branchlets 16. Taxodium. 



4. Cupressus Tribe. 

 A. Fr. a cone. 



B. Cone-scales all fertile, 4-8, forming appar- 

 ently 1 whorl: Ivs. usually scale-like, 

 opposite or in whorls of 3 or 4, rarely 



alternate on sterile branches 17. Callitria. 



BB. Cone-scales fertile at middle of cone and 



sterile at top and base 18. Fitzroya. 



BBB. Cone-scales partly fertile, partly empty, 

 arranged in opposite pairs: Ivs. scale-like, 

 opposite only on juvenile branches, some- 

 times needle-shaped. 

 c. Scales of cone imbricate. 



D. Seeds 4-5; pairs of scales 34 (exclud- 

 ing the upper connate pair) 19. Tkujopsia. 



DD. Seeds 2. 



E. Pairs of scales 4, the upper pair fertile.20. Libocedrua. 

 EE. Pairs of scales 6-8; the 2 upper pairs 



, fertile 21. Thuja. 



CC. Scales of cone peltate. 



D. Number of seeds 2; cones small. 



E. Wings of seeds very large, unequal. 22. Fokienia. 



EE. Wings of seeds narrow, equal 23. Cham&cyp- 



DD. Number of seeds many; cones usually [aria. 



rather large and woody 24. Cupressus. 



AA. Fr. fleshy, indehiscent berry or drupe, with 

 2-6 fertile scales: Ivs. scale-like, opposite 

 or needle-shaped and usually in 3's 25. Juniperua. 



Consult also the genus Athrotaxis, allied to Celphalotaxus and 

 Sequoia. 



181. CYCADACE.E. 



A. Lf.-segms. circinately involute in vernation: 

 female cones proliferous after anthesis; 

 scales elongate, the margins bearing 2 to 



many ovules I. 



AA. Lf.-segms. straight in vernation: female cones 



deciduous after anthesis; scales peltate. 

 B. Cone-scales superposed in vertical series. 

 c. Shield of the scales transversely 2-horned 



"apex . 2. Ceralozamia. 



cc. Shield of the scales truncate, not horned 



at apex 3. Zamia. 



BB. Cone-scales overlapping in alternating 



series. 



c. The !f.-segms. ribbed and nerved; nerves 

 spreading on either side of midrib, very 



numerous, simple or forked 4. Stangeria. 



cc. The If.-segms. with parallel, longitudinal 



nerves. 

 D. Shield of cone-scales flat, erect, ovate- 



cordate 5. Dioon. 



DD. Shield thickened, ascending, usually 

 prolonged into an erect, acuminate 



^blade 6. Macrozamia. 



DDD. fehield thickened truncate, decurved at 



apex 7. Encephal- 



{ctrtoa* 

 The genera Bowenia and Microcycas are also included. 



182. HYDROCHARITACE.E. 



A. St. elongated, submerged, everywhere leafy: 

 Ivs. short spathes small, sessile in axils: 



placentae little prominent in ovary 1. Elodta. 



AA. St. very short, sometimes emitting creeping 

 or floating stolons: Ivs. crowded, immersed, 

 sessile, elongated : spathes pedunculate : 

 placentae hardly prominent 2. Vallisneria. 



