Distinguishing Characteristics of Similar Species

FAM	Name	Distinguishing Characteristics
PTE	Cheilanthes covillei	leaf margin recurved; leaf surface beady on top, scaly on bottom
PTE	Cheilanthes parryi	leaf margin recurved; leaf grayish on top, woolly on bottom
PTE	Cheilanthes viscida	leaf margin recurved; leaf sticky on top
PTE	Notholaena californica	leaf margin recurved; leaf bottom with white exudate
PTE	Pentagramma triangularis ssp. maxonii	leaf margin flat; leaf bottom with white exudate; leaf top with yellow stalked glands
PTE	Pentagramma triangularis ssp. triangularis	leaf margin flat; leaf bottom with yellow exudate; leaf top glabrous
SEL	Selaginella eremophila	distinguished from moss by presence of roots
EPH	Ephedra aspera	2 leaves / node; seed 1 / cone, surface smooth
EPH	Ephedra californica	3 leaves / node, twigs not spiny
EPH	Ephedra fasciculata var. clokeyi	2 leaves / node; seed 1 / cone, surface furrowed
EPH	Ephedra nevadensis	2 leaves / node; seeds 2 / cone; cone stalked 1-5 mm
EPH	Ephedra trifurca	3 leaves / node, twigs spiny
EPH	Ephedra viridis	2 leaves / node; seeds 2 / cone; cone sessile or stalked 1-5 mm
ACA	Carlowrightia arizonica	Similar to Ditaxis lanceolata in gestalt, but leaves opposite
ASC	Asclepias albicans	few-stemmed; 6-12 feet high; lvs 2-3 / node; hoods < anther head
ASC	Asclepias subulata	many-stemmed; 3-6 feet high; lvs 2 / node; hoods >> anther head
ASC	Matelea parvifolia	filament column appendages fused into low structure around anther head
ASC	Sarcostemma cynanchoides ssp. hartwegii	pl sparsely hairy; corolla gen purple; filament column appendages free from ring of tissues at corolla base
ASC	Sarcostemma hirtellum	pl densely hairy; corolla gen greenish white; filament column appendages fused to ring of tissues at corolla base
AST	Adenophyllum porophylloides	somewhat similar to Porophyllum gracile, but lobed leaves with glands and often with sharp teeth
AST	Baccharis sergiloides	Similar to B. sarothroides, but pistillate pappus very short, 1-3 mm in fr; and larger lvs obovate. B. sarothroides has pappus 7-11 mm, and larger lvs linear
AST	Baileya multiradiata var. multiradiata	rays 15-many, bright yellow; invol 10+ mm diam; heads 1; ligules 10-20 mm, widely linear or oblong, prominently 3-lobed; peduncles gen 10-20+ cm, ~scape-like
AST	Baileya pauciradiata	rays 4-8, pale yellow; invol gen 4-6 mm diam; heads 2-3
AST	Baileya pleniradiata	rays 15-many, bright yellow; invol 10+ mm diam; heads 1; ligules 6-10 mm, widely elliptic to obovate, shallowly 3-lobed to truncate; peduncles gen 3-10 cm, gen leafy-bracted
AST	Brickellia arguta var. arguta	lvs sharply toothed
AST	Brickellia desertorum	pl 8-15 dm; lvs ovate; heads 8-12 fl'd, 8-10 mm; minutely tomentose
AST	Brickellia frutescens	pl 3-6 dm; lvs oblong to spoon-shaped; heads 20-30 fl'd, 13-15 mm, gen 1(3), terminal
AST	Calycoseris parryi	ligules yellow; tack-shaped glands dark-colored
AST	Calycoseris wrightii	ligules white; tack-shaped glands pale
AST	Chaenactis artemisiifolia	lower sts and lvs whitish granular-puberulent; largest lf blades (2)3-4 pinnately lobed, longest lobe near base; tips of longest phyllaries sharp but not acuminate, ~flat, green; lf tips flat; pappus 0
AST	Chaenactis carphoclinia var. carphoclinia	corolla white; tips of longest phyllaries acuminate, needle-like, cylindric, gen reddish;largest lf blades (2)3-4 pinnately lobed, longest lobe near base, bases of petioles not strongly enlarged; lvs basal and cauline, < 7 cm; bases of petioles not strongly enlarged
AST	Chaenactis carphoclinia var. peirsonii	corolla white; tips of longest phyllaries acuminate, needle-like, cylindric, gen reddish;largest lf blades (2)3-4 pinnately lobed, longest lobe near base, bases of petioles not strongly enlarged; lvs gen basal, longest 7-10 cm; bases of petioles strongly enlarged; RARE, east base of SnRsMtns
AST	Chaenactis fremontii	corolla white; outer phyllaries sharp, becoming glabrous;lvs entire or 1-pinnately lobed, lobes 1-2(5) pairs, well-separated, longest lobe gen near middle
AST	Chaenactis glabriuscula var. glabriuscula	corolla yellow
AST	Chaenactis stevioides	corolla white; outer phyllaries gen blunt, persistently glandular-hairy or cobwebby; largest lf blades entire or 1-2 pinnately lobed, longest lobe gen near middle
AST	Chaenactis xantiana	lower sts and lvs glabrous or +-cobwebby; largest lf blades entire or 1-2 pinnately lobed, longest lobe gen near middle; corolla white, longest phyllaries 10-18 mm, bases glabrous, tips densely puberulent; corollas radial; peduncles not glandular
AST	Chrysothamnus paniculatus	like Ericamera brachylepis, but phyllaries ~ 5 ranked in columns, midvein not prominently raised
AST	Chrysothamnus teretifolius	herbage gland-dotted; corollas yellow; phyllaries strongly vertically ranked, tips swollen, green
AST	*Conyza bonariensis	midvein of phyllary green to purple, not resin-filled; ligules ~ 0 mm
AST	Conyza canadensis	midvein of phyllary brown, resin-filled; ligules 0-1 mm
AST	Encelia actoni	heads solitary; rays present
AST	Encelia farinosa	heads in panicles; dead heads nodding, minute
AST	Encelia frutescens	heads solitary; rays absent
AST	Ericameria brachylepis	lvs thread-like; heads in raceme-like or narrowly panicle-like clusters at ends of leafy branches
AST	Ericameria cuneata var. spathulata	lvs obovate, 4-16 mm wide
AST	Ericameria linearifolia	lvs linear; head 1 per stem
AST	Eriophyllum multicaule	heads ~ sessile, peduncle < 5 mm; ray fls 5-7, ligules ~ 2 mm, yellow
AST	Eriophyllum wallacei	peduncle 1-3 cm; ray fls 5-10, ligules 3-4 mm, yellow to cream-white
AST	Filago arizonica	sts spreading, heads in groups of 4-10, restricted to forks and tips of branches; sts gen lfless between lower forks, ~glabrous, purplish to black
AST	Filago californica	sts ~erect, not forked, central axis dominant; heads in groups of 1-4, not restricted to forks and branch tips; sts ~evenly leafy between lower forks, cobwebby, grayish to greenish; lvs gen oblanceolate, acute
AST	Filago depressa	sts ~spreading, forked, central axis not dominant; heads in groups of 1-4, not restricted to forks and branch tips; sts ~evenly leafy between lower forks, cobwebby, grayish to greenish; lvs gen elliptic to obovate, obtuse
AST	Geraea canescens	lvs wing-petioled below, invol 7-12 mm; phyllaries narrowly lanceolate, acute, green ciliate; ray fls 10-21, ligules 1-2 cm
AST	Helianthus niveus ssp. canescens	central chaff scales tipped with stiff white hairs
AST	Helianthus niveus ssp. tephrodes	sand dunes; central chaff scales glabrous or very finely appressed-hairy
AST	Isocoma acradenia var. acradenia	lvs narrowly lanceolate, entire; invols 4-5 mm
AST	Isocoma acradenia var. eremophila	lvs narrowly obovate, with long-tapering base, to oboate, with 4-6 teeth per side; invols 5-7 mm
AST	Malacothrix californica	st scapose; lvs gen long-hairy near base
AST	Malacothrix glabrata	sts leafy, ~branched; basal lvs not long-hairy at base
AST	Pectis papposa var. papposa	herbage spicy-scented; mound-shaped; lvs narrowly linear, gland-dotted on margins; phyllaries 8, linear, each with subterminal gland and several smaller submarginal glands; rays 8; corollas 3-6 mm
AST	Porophyllum gracile	Somewhat similar to Adenophyllum porophylloides, but lvs entire, linear, glaucous
AST	Rafinesquia californica	ligules 5-8 mm, 3-5 mm beyond phyllaries
AST	Rafinesquia neomexicana	ligules 15-20 mm, 10+mm beyond phyllaries
AST	*Sonchus asper ssp. asper	basal lobes of lvs rounded
AST	*Sonchus oleraceus	basal lobes of lvs acute
AST	Stephanomeria exigua ssp. deanei	peduncles and invols strongly glandular; frs 2-2.5 mm
AST	Stephanomeria exigua ssp. exigua	peduncles and invols glabrous to sparsely glandular; frs 2.6-3.2 mm
AST	Stylocline gnaphaloides	lvs gen obtuse, uppermost < 13 mm, ~elliptic to obovate
AST	Stylocline micropoides	lvs acute, uppermost gen 11-15 mm, awl-like to lanceolate
AST	Trichoptilium incisum	gen tomentose or white-woolly; lvs mostly clustered in lower half, 1-3 cm; heads discoid, solitary; phyllaries in 2 ~equal series, free, 5-7 mm; pappus of 5 scales, each 5-7 mm, dissected into many bristles
AST	Viguiera parishii	pappus of 2 fringed scales (each 0.5-1.5 mm) and 2-3 lanceolate scales (each 2-3 mm)
BOR	Amsinckia menziesii var. intermedia	calyx lobes 5; corolla tube 10 veined near base; nutlet surface tubercled, sometimes ridged; corolla 7-11 mm, 4-10 mm wide at top
BOR	Amsinckia menziesii var. menziesii	calyx lobes 5; corolla tube 10 veined near base; nutlet surface tubercled, sometimes ridged; corolla 4-7 mm, 2-3 mm wide at top
BOR	Amsinckia tessellata var. tessellata	calyx lobes 2-4; corolla tube 20 veined near base; nutlet surface cobblestone-like or round-tubercled, ridged or not; corolla 8-12 mm, 2-6 mm wide at top
BOR	Cryptantha angustifolia	corolla width 1-5 mm; calyx 1-3.6 mm in fl, 2.5-4 mm in fr; nutlets 4
BOR	Cryptantha barbigera	corolla width 1-8 mm; calyx 4-6 mm in fl, 5-10 mm in fr; nutlets 1-4
BOR	Cryptantha costata	nutlets 4, sharp-angled; calyx in fl 3-4 mm
BOR	Cryptantha decipiens	like C. holoptera, but with spikes mostly in 2's; corolla width 1-5 mm; calyx 1.5-2.5 mm in fl, 2-4 mm in fr; nutlets 1-2
BOR	Cryptantha ganderi	corolla width 1-2 mm; calyx 3-4 mm in fl, 6-10 mm in fr; nutlets 1-2
BOR	Cryptantha holoptera	like C. decipiens, but with numerous short ascending branches; nutlets winged < 0.5 mm, wings not lobed
BOR	Cryptantha intermedia	corolla width 2-8 mm; calyx 2-3.2 mm in fl, 3.5-6 mm in fr; nutlets 1-4
BOR	Cryptantha maritima	corolla width 0.5-1.5 mm; calyx 1-2 mm in fl, 2-3.1 mm in fr; nutlets 1-2
BOR	Cryptantha micrantha	Plant gen wider than tall; flowers in dense bracted heads; calyx not circumscissile; root purplish
BOR	Cryptantha muricata	corolla width 1-8 mm; calyx 1-2 mm in fl, 2-4.2 mm in fr; nutlets 4(2-4)
BOR	Cryptantha nevadensis	corolla width 1-2 mm; calyx 1.8-4 mm in fl, 4-10 mm in fr; nutlets 4
BOR	Cryptantha pterocarya	nutlets winged 0.5-1.0 mm, wings lobed
BOR	Cryptantha pterocarya var. cycloptera	Plant tall, upright; flower appears to float out of a honking calyx, due to the wings on the nutlets
BOR	Cryptantha racemosa	perennial
CHE	Atriplex canescens ssp. canescens	shrub; fruit 4 winged, 4-25 mm
CHE	Atriplex lentiformis ssp. lentiformis	shrub; fr unwinged, 2-6 mm; lvs entire, ovate to deltate, gen 10-50 mm wide
CHE	Atriplex polycarpa	shrub; fr unwinged, 2-3 mm; lvs entire, oblong, 2-4 mm wide
FAB	Amorpha fruticosa	no glands on leaf rachis
FAB	Astragalus crotalariae	leaves green
HYD	Phacelia crenulata var. ambigua	like P. pedicellata, but with gray / yellow pollen, and pedicels shorter than calyx
HYD	Phacelia crenulata var. minutiflora	like P. pedicellata, but with gray / yellow pollen, and pedicels shorter than calyx
HYD	Phacelia pedicellata	like P. crenulata, but with blue/purple pollen and pedicels at least as long as calyx
KRA	Krameria erecta	spines barbed along shaft or smooth; flag petals fused at base
KRA	Krameria grayi	spines barbed only at tip; flag petals free
LOA	Mentzelia affinis	fruit 1 rowed above mid-ovary; seeds prism-like, 3 angled
LOA	Mentzelia albicaulis	fruit 2-3 rowed above mid-ovary; seeds grain-like
RHA	Ziziphus parryi var. parryi	Similar in habit to Prunus fremontii, but leaf elliptic to obovate, margin ~entire; fr glabrous; petals yellow
ROS	Prunus fremontii	Similar in habit to Ziziphus parryi, but leaf ovate to round, crenulate to serrate (you "prunus with a saw"), fruit puberulent; petals white
TYP	Typha domingensis	pistillate stalks peg-like, not hair-like

http://tchester.org/bd/species/similar_species.html
Updated 20 November 2009.