The identity of Erythrina princeps

An examination of available evidence leads to the conclusion that  Erythrina princeps A. Dietr. must be regarded as a synonym of  E. humeana Spreng.

E. princeps w as described from a p lan t o f unk n o w n origin grow n in the Berlin B otanic G a rd e n an d u n fo rtu n a te ly the specim ens know n to have existed were d estro y ed d u rin g W orld W a r II.H ow ever, a p h o to g ra p h o f the type specim en w as tak en in 1929 by the F ield M useum o f N a tu ra l H istory, C hicago, a n d th e ir negative N o.2375 is designated by K ru k o ff a n d B arn ab y as the neotype.A t the req u est o f D r K ru k o ff, the Field M useum kindly sent m e a p rin t from th is negative, w hich is rep ro d u ced here, w ith th e ir p erm ission, as Fig. 1.

t . 4
A n exam ination o f this p rin t shows th at it does not agree w ith E. lysistemon, which has a dense, com pact inflorescence (Fig. 2).In fact, it agrees in all respects w ith E. humeana Spreng.Fig. 3 is a photo g rap h o f Bot.Reg. t. 736A (1823), which m ay be regarded as typifying E. humeana (see discussion below), and Fig. 4 shows a m odern herbarium specimen o f this species.
Before W orld W ar II, D r K ru k o ff exam ined a dissected flower from an authentic specimen of E. princeps grow n in Berlin Botanic G arden in 1844, which was am ong those destroyed during the war.He describes it as a narrow , declined flower with included androecium th a t characterizes E. lysistemon.It m ay be pointed out th a t this characteristic, while serving to separate E. lysistemon from E. caffra, as was D r K ru k o ff's intention, could apply equally well to E. humeana as to E. lysistemon.
In ad d itio n to the m arkedly elongate inflorescence o f E. humeana, w ith spaced verticils o f flowers, there is a slight difference in the vexillum shape which assists in distinguishing this species from E. lysistemon.In E. humeana the vexillum is broadest tow ards the apex producing an obtuse to clavate appearance while, in E. lysistemon, the vexillum is broadest near the m iddle an d tapers tow ards the apex.In this respect also, the type o f E. princeps resembles E. humeana.
A n im p o rtan t character w orth noting is the presence o f prickles on the petiole, showing in the type o f E. princeps and m entioned in the original description.This is a co n stan t characteristic o f E. humeana b u t in E. lysistemon the presence o f an occasional prickle on the petiole m ay be regarded as exceptional.Historically it is m ost unlikely th a t E. lysistemon could have been grown to the flowering stage in Europe by 1834.It has been observed here in Pretoria th at this species takes at least 10 years from sowing to flowering, which would necessitate its introduc tion to Europe before about 1824.E. lysistemon reaches its southernm ost distribution in the Transkei, a region unexplored botanically before Drege made his m om entous journey from the eastern Cape Province to N atal in 1832.A lthough E. lysistemon is com m on near " P ort N atal" , this territory was also virtually unexplored until the arrival in 1838 o f the naturalists, K rauss and W ahlberg.
There is no evidence th at E. lysistemon was success fully cultivated in Europe until the latter part o f the 19th century and than possibly only in the M editer ranean region.As stated by K rukoff and Barnaby, E. princeps (i.e.E. humeana) was widely grown in European stoves by the mid 19th century.

E. humeana was originally figured in England as
E. caffra in Bot.Reg.9: t. 736 A & B (1823): " in tro duced into this country by Sir A braham Hume, in whose collection at W orm leybury the draw ing was m ade" , and in Bot.Mag. t.2431Mag. t. (1823)): " flowered for the first time, we believe, in the C ount de Vandes stove."Both publications appeared on 1 Septem ber 1823.In 1826 C. Sprengel realised that the figured plant was distinct from E. caffra and renam ed it E. humeana.In his protologue Sprengel refers only to " Brot.Vag.'\ which may be interpreted as Bot.Mag.However, it seems probable that he was aware o f both plates because only in the Bot.Reg.text is the nam e Hume m entioned.The Bot. Reg.plate No. 736A is, therefore, selected as the lectotype.(

F
i g .2.-E r y th r in a ly s is t e m o n Hutch.(Codd 7987 from Mqanduli) showing the dense, compact inflorescence o f this species.
humeana S p r e n g a m odern herbarium specimen from the eastern C ape P rovince (C odd 9297).The species is d istrib u te d fro m A lb a n y a n d B a th u rst districts to N a ta l a n d n o rth w a rd s to S w azilan d , eastern T ran sv aal, M o z a m b iq u e , R h o d e sia a n d Malawi.T he typical fo rm , w ith b ro a d ly o v ate leaf lets, occurs in the e a ste rn C a p e P ro v in ce w hile, further no rth , a form w ith h a sta te leaflets is fo u n d (Fig. 5).T his form h as been d escrib ed as E. raja Meisn.(after R aja, a genus o f fishes, in allu sio n to the aculeate petioles) a n d as E. hastifolia B ertol.f. but, because there are in te rm e d ia te s, it is felt th a t th is form is not w o rth y o f se p a ra te ta x o n o m ic sta tu s.The synonym y relating to E. humeana is sh o w n below.Krvthrina hum eana S p r e n g Syst.Veg.3: 243 (1826); Sim, F o r.FI.P .E .A .43 (1909); P h illip s in Flow.PI. S. A fr. 3: t.l 12 (1923); M a rlo th , FI. S. A fr., 2 ,1 : 81, t.29 (1925); C o llett in B o th alia 4 a S p r e n g illustrating the form w ith hastate leaflets described as E. raja M eisn.and E. hastifolia Bertol.f. ( C odd & D yer 4636 from north-eastern T ransvaal).